BEIRUT (AP) — Regime airstrikes hit a gas station in northern Syria Thursday, setting off a fiery explosion that killed at least 30 people and wounded dozens, opposition activists said. Amateur video showed thick black smoke engulfing the scene.

Earlier Thursday, a Syrian military helicopter crashed near the capital of Damascus, and Syria’s Information Ministry said the helicopter went down after its rotor accidentally clipped the tail of a Syrian passenger plane with 200 people on board. The larger aircraft landed safely at Damascus International Airport and no one was hurt, the ministry said.

The airstrikes and the close call in the sky underscored the growing turmoil and violence in Syria. The country is embroiled in a civil war between forces fighting for President Bashar Assad and those trying to topple him. More than 23,000 people have been killed in the 18-month conflict, according to activists.

In recent weeks, Assad’s regime has stepped up airstrikes in northern Syria in an attempt to dislodge rebels from areas they control there. Activists said Thursday’s air attack hit near the town of Ain Issa, about 25 miles (40 kilometers) from Turkey. A day earlier, rebel fighters had seized control of a border crossing north of the town.

Rami Abdul-Rahman of the Britain-based Syrian Observatory for Human Rights, said that witnesses counted at least 30 bodies and that dozens of people were wounded. Another group, the Local Coordination Committees, which gathers information from a network of activists across Syria, put the death toll at 55. Other reports put the death toll as high as 70.

Amateur video showed thick black smoke rising near the gas station, which was partially intact. Several vehicles, including a bulldozer and pickup trucks, were on fire. The video, whose authenticity could not be confirmed independently, also showed several damaged cars. A man could be heard shouting “your son is dead.”

Both groups quoted witnesses as saying the blast was caused by airstrikes on the gas station.

The Syrian conflict appears to have reached a stalemate. The rebels are holding some territory despite the government’s military superiority but have been unable to score decisive victories. At the same time, the international community is averse to getting involved militarily and instead hopes economic sanctions will squeeze the Assad regime.

Meanwhile, the fighting continues.

Across Syria, at least 184 people were killed Thursday, the LCC said, reporting 35 dead in Aleppo, Syria’s largest city, and 32 in Damascus and its suburbs. The Observatory put the day’s total across Syria at 162. August has been the deadliest month so far in the Syria conflict, with activists saying nearly 5,000 were killed.

The crash near Damascus came after the rotor of a military helicopter clipped the tail of a Syrian Arab Airlines jet, the state-run news agency SANA quoted Syria’s Information Ministry as saying. This seemed to counter speculation that anti-regime fighters might have downed the helicopter.

Rebels in Syria are fighting mostly with light weapons. Opposition fighters have claimed to have shot down helicopters and warplanes in the past, although the regime blamed most of the problems on mechanical difficulties.

Syrian officials did not report any casualties in the helicopter crash, saying only that it went down in Adra, a Damascus suburb. Adra is near the Douma district, which has witnessed repeated military crackdowns to purge the rebels.

“We heard the sound of several explosions and some gunfire, and a few minutes later, we were told that a helicopter had crashed,” Mohammad Saeed, an activist in Douma, said via Skype. He said the helicopter went down near a factory for household items, adding that Syrian MiG warplanes and helicopter gunships had been flying low over the area before the crash.

Hitting Assad’s wallet

On the diplomatic front, a coalition including the United States, the European Union and the Arab League met in the Netherlands to search for new ways of isolating the Assad regime. The group called “Friends of the Syrian People” was set up in February after the U.N. Security Council was unable to agree on a resolution condemning Syria’s government, due to opposition from Russia and China.

Financial experts joined representatives of the group at their meeting in The Hague to help member countries understand how Syria may be using dual-use technologies and front companies to get around the existing sanctions, which include an embargo on oil and arms trade with Syria by participating nations.

Dutch Foreign Minister Uri Rosenthal said the sanctions are having an effect, despite non-participation by Russia, China and Iran, citing a sharp fall in Syria’s oil exports. Syrian opposition leaders have warned that sanctions alone will not topple Assad.

Shelling and gunfire also echoed across the northern border region with Turkey, a day after rebels seized control of the strategic Tel Abyad border crossing there. The Observatory reported renewed fighting near the crossing. Tel Abyad is about 40 kilometers (25 miles) north of where the gas station was struck Thursday.

In Akcakale, a Turkish hamlet that straddles the border, a large explosion was heard. In the distance in Syria, military vehicles were seen rushing toward the blast scene as smoke billowed from the area.

Akcakale authorities closed local schools for a second straight day.

Turkish police vehicles escorted reporters covering the events in Syria away from the border. Turkish security forces were also seen moving local residents and cordoning off the area closest to Syria.

Residents of Akcakale said they fear for their safety.

“We’re pretty scared. I’m not letting my children out of the house. I’ve sent them (the children) to another village, 5-10 kilometers from here,” said resident Mehmet Resat Guvenic. “We’re afraid because this is the first time we’re hearing gunfire, and bombings, and shelling.”

Following the continuing violence and soaring death toll, a coalition including the United States, the European Union and the Arab League met Thursday to plot new ways of isolating the regime of Syria’s President Bashar Assad, and a Syrian opposition leader warned that sanctions alone won’t bring the regime down.

The group called Friends of the Syrian People was set up in February after the UN Security Council was unable to reach agreement on a resolution condemning Syria’s government, due to opposition from Russia and China.

On Thursday, financial experts joined representatives of the group at their meeting in a coastal suburb of The Hague, Netherlands, to help member countries understand how Syria may be relying on dual-use technologies and front companies to get around the existing sanctions, which include an embargo on oil and arms. Twelve more countries have joined the 60-member coalition, committing also to block Syrian financial transactions and to enforce a travel ban on the country’s top leaders.

The uprising against the Syrian government began in March 2011 as part of Arab Spring protests and intensified after Assad’s government used the country’s military in an attempt to end the unrest. The United Nations estimates that at least 18,000 people have been killed as a result of the fighting, most of them civilians. More than 1.5 million people have been displaced, many fleeing as refugees to neighboring countries such as Turkey and Jordan.

Dutch Foreign Minister Uri Rosenthal said the sanctions are having an effect, despite non-participation by Russia, China and Iran, citing a sharp fall in Syria’s oil exports. “The EU took 90 percent of Syria’s oil,” before the sanctions were applied, he said. “It turns out to be hard for the regime to sell oil elsewhere.”

Abrahim Miro — a member of the Syrian Governing Council, an umbrella organization of Syrian opposition groups cooperating to overthrow the government — said the sanctions alone will not bring Assad’s regime down. He said he hopes increased sanctions and the armed resistance by the Syrian Free Army “will actually cause the economic heart attack and also the military heart attack of the regime.”

Miro said Syria’s continued trade with Iraq and Iran — which were not represented at Thursday’s meeting — is a major source of concern for the opposition.

Abdo Hussameldin — a former official in Syria’s oil ministry, who in March became the highest-ranking member of the government to defect — said the economic sanctions are demoralizing and delegitimizing the regime in the eyes of the country’s people. But he agreed with Miro that the sanctions alone won’t force Assad from office as long as his regime continues to get financial support from countries such as Russia, Iraq, Iran, Venezuela and Lebanon.

In a closing statement, the Friends of Syria coalition called on banks and companies to adhere to the sanctions, even if their government is not a member, or risk damage to their reputation and jeopardize their relations with the rest of the business world.

The Friends of Syria group agreed to meet again in Japan before the end of 2012, though no date was set.