Two homicide attackers detonated their bombs inside the police headquarters in Afghanistan's second-largest city Sunday, killing at least two police and wounding 37 people, officials said.

The two bombers targeted Gen. Abdul Raziq, a border police commander, two police officers at the scene in Kandahar said. The blasts went off within a minute of each other, one on a ground floor and one on an upper floor, officials said.

The governor's spokesman, Najib Pervaiz, said two police were killed and 29 police and eight civilians were wounded. He said 16 of the wounded were in critical condition.

One high-ranking officer, who asked not to be identified because he wasn't authorized to speak to the media, said six police were killed and 13 wounded, including Raziq. It wasn't immediately possible to reconcile the different figures.

"The bomber wanted to get close to Gen. Raziq, but his guards stopped him," Karim Agha, a police officer wounded in the attack, told The Associated Press from his hospital bed. "After that I don't know what happened. I went unconscious."

Canadian troops and Afghan soldiers surrounded the police headquarters shortly after the explosions.

Kandahar is the Taliban's former stronghold. Militants unleashed a massive attack on the city's prison in June, killing around nine police and setting free almost 900 prisoners.

In other violence, U.S. coalition troops targeted insurgents fighting under a wanted militant leader in eastern Afghanistan, killing more than 10 armed fighters and detaining seven, the coalition said Sunday.

The operations — three over two days — targeted the militants for conducting and coordinating suicide and other attacks in the eastern province of Khost, the coalition said.

It said the militants belonged to the network of Siraj Haqqani, the son of longtime warlord Jalalludin Haqqani. The U.S. has called Siraq Haqqani a ruthless new brand of militant leader and last year announced a $200,000 reward for information leading to his capture.

Haqqani, a Taliban-associated militant with close ties to Al Qaeda, is accused of masterminding beheadings and massive suicide bombings. He is believed to be in Pakistan.

The coalition said more than 10 armed militants were killed during a U.S. operation Saturday that involved ground forces, attack helicopters and airstrikes.

Separately, the Helmand province police chief said militants attacked a police patrol Saturday and wounded four officers. Mohammad Hussein Andiwal said police returned fire and killed 11 militants in the battle in the Nad Ali district.

More than 4,000 people have died in insurgency-related violence this year, according to an Associated Press tally of figures from Western and Afghan officials.