JERUSALEM -- A bomb struck a crowded bus stop in central Jerusalem Wednesday, wounding some 25 people in what authorities said was the first major Palestinian militant attack in the city in several years.
The bombing brought back memories of the second Palestinian uprising last decade, a period in which hundreds of Israelis were killed by suicide bombings in Jerusalem and other major cities.
There was no immediate claim of responsibility, but Israeli police blamed Palestinian militants. The attack comes as tensions have been escalating between the two sides. In recent days, Hamas and other armed groups in the neighboring Gaza Strip have been firing rockets and mortars into Israel, prompting Israeli reprisals.
"We are talking about a terror attack," said police spokesman Micky Rosenfeld.
Israel's public security minister, Yitzhak Aharonovich, told Channel 2 TV that the bomb was about four pounds (one to two kilograms) and was planted in a small bag on the sidewalk. He said security services were on alert for additional attacks.
The 3 p.m. attack occurred near the main entrance to Jerusalem, next to the city's central bus station, an area that is crowded with travelers and passers-by at all hours of the day.
The blast reverberated throughout Jerusalem and blew out the windows of two crowded buses. Rescuers removed bloodied people from the area on stretchers, as sirens from speeding ambulances wailed in the background.
Israel's national rescue service said 25 people were wounded, including four in critical condition. No deaths were reported.
Jerusalem's police chief, Aharon Franco, said there were no firm leads but authorities were investigating a possible link to a small bombing earlier this month that wounded a garbage collector as he removed the device from a trash can.
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.
Police said the bomb had been planted next to a payphone.
Samuel Conik, 20, said he ran to the scene when he heard the explosion and saw fire coming out of a phone booth. Nearby was a badly burned man with bloody legs and his skin peeling off.
Prime Minister Benjamin Netanyahu's office said the Israeli leader had decided to postpone a planned trip to Moscow on Thursday to deal with the crisis.
Police, accompanied by sniffer dogs, broke into cars near the site to search for evidence and possible additional explosives.
In the Gaza Strip, the Islamic Jihad militant group, which has carried out dozens of attacks, said it was not connected to the blast. But spokesman Khader Habib said the group "applauds all efforts to respond to the crimes committed daily against our people."
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, and the last suicide bombing in Israel occurred in 2008 in the southern town of Dimona.
Even so, the city has experienced other deadly violence. In early 2008, eight students at a Jerusalem seminary were killed when Palestinian gunmen entered the school and opened fire.
Palestinians also carried out several attacks with construction vehicles against Jerusalem in the past few years that ended with fatalities when the drivers rammed their vehicles into bystanders.
Earlier this month, five members of a family in a West Bank settlement were knifed to death as they slept.