At least 10 people were injured in an explosion on a bus near the defence ministry in Tel Aviv on Wednesday, Israel's emergency services said, in what an official said was "a terrorist attack."
The blast took place as US Secretary of State Hillary Clinton was in Israel for talks with Prime Minister Benjamin Netanyahu on ways to end a deadly spike in bloodshed in and around Gaza over the past week.
"There are at least 10 people wounded of whom three are in serious condition," emergency services spokesman Zaki Heller told Israeli public radio.
Police said the blast took place on a street which runs just behind the Kiriya, Israel's sprawling defence ministry.
"There was an apparent explosion on a bus in Shaul HaMelech Street in Tel Aviv. The background and circumstances are not clear yet," police spokeswoman Luba Samri said.
TV images showed the bus with its windows blown out and its metal frame contorted from the force of the blast, in images reminiscent of scenes from the 2000-2005 Palestinian uprising.
The front window was completely shattered and glass littered the floor as the wounded were loaded into ambulances by an army of medics.
Netanyahu's spokesman said it was "a terrorist attack."
"A bomb exploded on a bus in central Tel Aviv. This was a terrorist attack. Most of the injured suffered only mild injuries," said Ofir Gendelman on his official Twitter account.
The blast came as Clinton held talks in Jerusalem over a Gaza truce with Netanyahu, with a US embassy spokesman confirming the two had held their second round of talks in as many days.
Israel has been locked in a deadly week-long confrontation with Palestinian militants in Gaza.