Security forces maintained a state of increased readiness from Tuesday evening and into Wednesday in response to intelligence received by the Shin Bet security service indicating the possibility of a terror attack in the city.

Magen David Adom ambulance service declared a “Level C” alert, the second-highest level of readiness. Later they raised the alert to the highest level. Local firefighters were also on standby.

A police helicopter was patrolling the skies above the capital, and other units were deployed on Tuesday. There were also roadblocks at entrances to the city, and vehicles leaving nearby Arab villages were being checked.

The fear was of a terror attack, possibly by a suicide bomber, but the alert was “general, rather than specific,” security sources said.

Israeli officials have warned of an upsurge in attacks on Israelis from the West Bank of late. An annual survey released late last month said there had been an increase in the number of terror attacks carried out against Israelis in 2012 compared to 2011, but it was accompanied by a decrease in the number of fatalities.

According to the annual Shin Bet report, the number of terror attacks in the West Bank rose from 320 in 2011 to 578 in 2012, while 282 attacks were carried out in Jerusalem, compared to 191 in 2011.

According to the report, the increase was due in part to a 68% rise in what the Shin Bet refers to as “popular” terror attacks — mainly attacks involving Molotov cocktails. However, the number of attacks involving firearms and explosives also grew by 42% — 37 compared to 26 in 2011.

Ten Israelis were killed as a result of terror attacks in 2012, compared to 22 killed in 2011. Six of the victims were civilians and four were members of the security forces.