JERUSALEM -- A Palestinian driving an enormous construction vehicle went on a deadly rampage on a busy Jerusalem street Wednesday, plowing into a string of cars, buses and pedestrians, killing at least three people and wounding at least 45 before he was shot dead by security officers.

The violence, the first major attack in Jerusalem since March, wreaked havoc and left a large swath of damage in the heart of downtown Jerusalem. Traffic was halted, and hundreds of people fled through the streets in panic as medics treated the wounded.

Half a dozen cars were flattened and others were overturned by the Caterpillar vehicle. A bus also was overturned, and another bus was heavily damaged. Israel's national rescue service confirmed three deaths.

Three Palestinian militant groups took responsibility for the attack included the Al-Aqsa Martyrs' Brigade, which is loosely affiliated with Palestinian President Mahmoud Abbas' Fatah movement. The other two are the Galilee Freedom Battalion, which is suspected of being affiliated with Lebanon's Hezbollah guerrillas, and the Popular Front for the Liberation of Palestine, a fringe left-wing militant group.

The Hamas militant group, which runs the Gaza Strip and is currently maintaining a fragile cease-fire with Israel, said it did not carry out the attack but nevertheless praised it.

"We consider it as a natural reaction to the daily aggression and crimes committed against our people in the West Bank and all over the occupied lands," Hamas spokesman Sami Abu Zuhri said.

Despite the Palestinian claims of responsibility, Israeli police chief Dudi Cohen said the attacker appeared to be acting alone.

"It looks as if it was a spontaneous act," he said.