An explosion in a trolleybus Monday killed at least 14 people in the second suicide attack in the Russian city Volgograd in as many days, raising the specter of violence at the upcoming winter Olympics in the nearby city of Sochi.

The explosion took place shortly after 830 a.m. local time, during morning rush hour near a local shopping district. The trolleybus was completely destroyed in the blast.

According to reports, a one-year-old infant is among the dead. At least 25 were wounded, many of them severely.

Russian officials have confirmed the attack was committed by a male suicide bomber connected to Islamist terror groups in southern Russia.

Suicide bombings have rocked Russia for years, but most have been in the North Caucasus region, the center of an insurgency seeking an Islamist state in the region. But Volgograd, formerly known as Stalingrad, has been struck three times in two months — suggesting militants may be using the transportation hub as a renewed way of showing their reach outside their restive region.

A suicide bus bombing in Volgograd in October killed six people.

The Monday attack came less than 20 hours after a bombing Sunday of a local train station that killed 17 and wounded over 30.

There was no immediate claim of responsibility for either explosion, which came several months after Chechen Islamist rebel leader Doku Umarov called for new attacks against civilian targets in Russia, including the Sochi Games.

Russian President Vladimir Putin called a meeting of the country’s security chiefs in the Kremlin immediately after the attack.

AP contributed to this report.