An bomb tied to a telephone pole exploded Wednesday at a crowded bus stop outside the International Convention Center in Jerusalem, just opposite the central station.

At least 25 people were wounded in the incident, four of them seriously. All of the casualties have been evacuated to the Hadassah Hospital in Ein Karem. The Magen David Adom emergency services said that there were no fatalities.

The blast could be heard throughout Jerusalem and blew out the windows of two crowded buses, No. 74 and No. 14.

An eyewitness in the area at the time of the explosion told Haaretz that she heard a loud blast close to the central bus station and second later sirens began to wail and security forces rushed to the scene.

Meir Hagid, one of the bus drivers, said he heard a loud explosion as he drove by the site, located near the main entrance to Jerusalem and its central bus station.

"I heard the explosion in the bus stop," he said. He halted his vehicle and people got off. He said nobody in his bus was hurt.

Jerusalem suffered dozens of suicide bombings that targeted buses and restaurants during the second Palestinian uprising last decade. But the attacks have halted in recent years. Jerusalem last experienced a suicide bombing in 2004.

The entrance to the city has been closed. Security forces were combing the area for other suspicious packages or objects.

Jerusalem has been hit by a number of terror attacks over the last few years, two of them involving tractor drivers that ploughed down a central street.

Jerusalem suffered dozens of suicide bombings that targeted buses and restaurants during the second Palestinian uprising last decade. But the attacks have halted in recent years. Jerusalem last experienced a suicide bombing in 2004.