21/11/2012 05:59 GMT | Updated 21/11/2012 09:50 GMT

Tel Aviv Bus Explosion Injures At Least 21, Israeli Police Suspect Terror Attack (PICTURES, VIDEO)

Twenty-one people have been injured in a bus bomb a block away from the headquarters of the Israeli Defence Force (IDF) in Tel Aviv on Wednesday, in what Israeli police have described as a terror attack.

The bomb was reportedly attached to the bus and not a suicide attack. The Jewish Chronicle has reported that the police are still searching for the culprit.

Foreign secretary William Hague said he was "deeply concerned" at the reports of an explosion, which follows a week of violence after Israel launched 'Operation Pillar of Defence' by assassinating the head of Hamas' military wing Ahmed Said Khalil al-Jabari. Around 130 Palestinians and five Israel have died in the ensuing conflict.

An Israeli security officer stands next to a blown up bus at the site of a bombing in Tel Aviv

Speaking at prime minister's questions on Wednesday afternoon Ed Miliband and David Cameron called the attack "appalling."

David Cameron told MPs the European Union and America needed to pressure Israel and those who have contacts with Hamas to "de-escalate."

"We need a ceasefire and then beyond that what we need is proper discussion about the future of Israel and Palestine."

According to the BBC's Paul Danahar there was celebratory gunfire in Gaza as news of the attack broke.

Hamas spokesman, Sami Abu Zuhri, told Reuters they saw "it as a natural response to the Israeli massacres... in Gaza."

Tel Aviv, Israel's largest city, has not been hit by a significant bomb blast since a suicide bomb which killed 11 in April 2006.

Israeli Police spokesperson Mickey Rosenfeld said at least 15 people were injured, three "moderately."

"We do believe it was a terrorist attack," he said.

According to Aljazeera, witnesses saw a man leave a bomb on the bus and then run off.

The bomb exploded near military headquarters with IDF spokesperson Avital Leibovich tweeting: "A bus explodes under my Tel Aviv office. Possibly due to a bomb or suicide bomber. Hearing the sirens of the ambulances."

Ofir Gendelman, a spokesman for Israel's prime minister Benjamin Netanyahu, said: "A bomb exploded on a bus in central Tel Aviv. This was a terrorist attack. Most of the injured suffered only mild injuries."

The bomb exploded near military headquarters

William Hague said: "At this time our thoughts are with the individuals and families affected.

Israeli rescue workers and paramedics carry a wounded person from the site of a bombing in Tel Aviv

"Details of what happened are still unclear but if this was a terrorist attack we condemn it unreservedly. We are clear that terrorists must not be allowed to set the agenda.

"This shocking violence further underlines the urgent need for an immediate de-escalation of violence and a full ceasefire. We urge all those involved to do everything they can to give maximum support to Egyptian-led efforts to allow them to succeed."