Two bombs exploded at a gathering of Sunni Muslim radicals (search) in the central Pakistan city of Multan (search) before dawn Thursday, killing 39 people and wounding about 100, police said.

Police immediately suspected a sectarian attack. The bombing comes less than a week after a suicide attack left 31 dead at a Shiite mosque in an eastern city.

About 3,000 people had gathered in a residential area of Multan to mark the first anniversary of the killing of the leader of the outlawed Sunni radical group, Sipah-e-Sahaba (search).

A car bomb exploded near the venue as people were starting to disperse after the overnight meeting, and two minutes later a second bomb attached to a motorcycle went off, deputy city police chief Arshad Hameed said.

"It seems to be an act of sectarian terrorism, but we are still investigating," he told The Associated Press.

Officials at the Nishtar government hospital said at least 39 people were killed and more than 100 people were wounded, about 50 seriously. Some 50 others were treated for minor injuries and later discharged. Other people had been taken to other clinics.

Hameed said the car blew up minutes after a man had parked it, and it was probably detonated by remote control. Explosive experts were sifting through the debris, trying to collect pieces of the bomb.

"It seems to be an act of sectarian terrorism, but we are still investigating," he said.

Multan police chief Sikander Hayyat told the private Geo television network that it did not appear to be a suicide attack as no body parts were found inside the car.

Witnesses said about 2,000 angry Sunnis gathered outside the Nishtar hospital after the bombings, shouting "Shiites are infidels!" Police said they were stepping up security in the city, which has suffered sectarian violence in the past.

Sunni Muslims make up about 80 percent of the 150 million people in Pakistan, and most of the rest are Shiites. The vast majority of both sects live in harmony but radical elements on both sides carry out attacks.

"We condemn this terrorist attack. This is tragic," Information Minister Sheikh Rashid Ahmed told The Associated Press in the capital Islamabad. "The government will continue its mission against terrorism."

The first blast happened around 4:40 a.m. as the gathering was praying for Sipah-e-Sahaba leader Maulana Azam Tariq, who was gunned down on the outskirts of Islamabad last year. The attack was blamed on Shiite Muslim militants.

A leader of the group said he believed Thursday's bombings were a sectarian attack by radical Shiite Muslims.

"This is the worst kind of terrorism, and everybody knows who is behind it," said Ahmad Ludhianvi, the head of Sipah-e-Sahaba.

He said that about 3,000 people were at the gathering, which was held overnight in an open area in Multan's Rashidabad neighborhood. The vehicles that exploded were parked nearby, he said.

Ayub Rana, a witness who had been leaving the gathering, said the two explosions happened one after the other and left a scene of carnage.

"As we were coming out there was an explosion and set the car on fire. Then there was another explosion in the motorcycle," Rana said.

Blood and shoes of the victims were scattered at the scene, near the burned-out wreckage of the car.

Jamil Usmani, 26, who had been standing in a nearby parking lot with friends, said a stampede after the bombing caused many injuries.

"The explosion numbed our ears, we saw people falling on each other, everybody was crying, everybody was running," he said.

"Many people were injured in the stampede, we started picking them up and asked passing cars for help," he said.

From his hospital bed, Mohammed Nawaz, 23, said he was knocked to the ground by a blast, and saw the burning wreck of the car and a nearby electricity transformer on fire. His head and one hand were bandaged.

"I heard an explosion when I came out, then I don't know what happened," said Mohammed Arshad, 36, who suffered a serious leg injury. "I gained consciousness in the hospital."

Pakistan, a key ally in the U.S.-led war on terrorism, has suffered a spate of terrorist attacks in recent years, and has a history of sectarian violence.

Thursday's blasts came six days after a suicide attacker detonated a bomb inside a crowded Shiite mosque in the eastern city of Sialkot Friday prayers, killing 31 people and injuring more than 50.

The attack also came hours after the burial of an alleged top al-Qaida operative and Sunni Muslim militant, Amjad Hussain Farooqi, at a village in eastern Punjab province.

Farooqi was killed in a shootout with security forces Sept. 26 in southern Pakistan. He was a member of Lashkar-e-Jhangvi, a breakaway militant faction of Sipah-e-Sahaba, and had been accused in attacks on Shiites, and in the 2002 kidnapping and beheading of American journalist Daniel Pearl.