Deadly Syrian blast shreds Damascus police bus.

An explosion ripped through a busy intersection in the Syrian capital Friday, hitting a police bus and killing at least 11 people and possibly many more in an attack that left pools of blood in the streets and marked the second deadly attack in the capital in as many weeks, Syrian authorities said.

Interior Minister Mohammed Shaar blamed a suicide bomber for the blast, which comes exactly two weeks after twin bombings in the capital killed 44 people. The bombings mark a dramatic escalation of bloodshed as Arab League observers tour the country to investigate President Bashar Assad's bloody crackdown on a 10-month-old popular revolt.

"He detonated himself with the aim of killing the largest number of people," Shaar said.

Syrian television showed residents and paramedics carrying human remains, holding them up for the camera. Other footage showed a police bus with blood on its seats, and cars with blown-out windows and riddled with shrapnel.

CBS News' George Baghdadi reported from the scene that the state-owned bus was totally destroyed, and a number of cars in the vicinity also were heavily damaged and splattered with blood.

Baghdadi says the attack hit in the heart of Damascus, only about 10 yards from the local police station.

An Associated Press reporter at the scene said the blast also damaged the police station, shattering its glass, and that there was blood and flesh in the streets. Police cordoned off the area with yellow police tape.

Shaar said 11 people have been confirmed dead. Authorities believe another 14 were also killed, based on human remains from the scene, which would bring the death toll to 25, state TV said. More than 60 people were wounded.

In a sign of just how polarized Syria has become, the opposition has questioned the government's allegations that terrorists are behind the attacks — suggesting the regime itself could have been behind the violence to try to erode support for the uprising and show the observer team that it is a victim in the country's upheaval.

Baghdadi reports that in the aftermath of the blast, an anti-Assad demonstration sprang up in the area, but those opposition supporters quickly disappeared as security forces sealed off the area.

Soon after, hundreds of pro-Assad demonstrators descended on the area, carrying banners and signs expressing support for the leader and chanting his name.

Baghdadi says the situation in Damascus has become dramatically more tense in recent weeks, with many residents trying to remain in their homes when possible.