U.S. Consul General John Bauman said a camera mounted on the outside of the building recorded the shooting, according to police who spoke to him. 

Bauman ventured outside the consulate briefly to inspect the site and meet police officers. 

"We are trying to get details from the Pakistani authorities about it," said Terry White, spokesman for the U.S. Embassy in Islamabad. "I understand the local police are investigating it, and we hope they will be able to determine who were the attackers and what was their purpose." 

The United States already has evacuated family members from Pakistan as have most foreign missions here. A U.S. Embassy worker and her daughter were killed last March in an attack on a nondenominational church in the Pakistani capital. 

"We are very security conscious, fortunately we are getting excellent cooperation from the Pakistani security agencies," White said. 

Pakistan's Information Minister Sheikh Rashid Ahmed said his government was saddened by the attack and the deaths of the policemen. 

"This is a tragic incident," Ahmed said in an interview with The Associated Press. "We are a target for terrorists. These people, whoever they are, are enemies of our country and are out to harm Pakistan's image." 

Security has been intense around the U.S. facility since a bombing last June killed 12 people, all Pakistanis. Cement barricades stop vehicles from entering the area, set up to prevent car bombings. High walls surround the consulate and entry and exit from the building is closely guarded. 

Five suspects accused of masterminding the June bombing are on trial in the southern port city, charged with conspiracy, murder and terrorism. They face the death penalty if convicted. 

The car bombing was one of a series of attacks on foreigners and minority Christians in Pakistan since President Gen. Pervez Musharraf threw his support behind the U.S.-led war against terrorism. 

There has been a great deal of public outrage over a possible war on Iraq and warnings of violence should Pakistan's President Pervez Musharraf support the United States against Baghdad. 

Both Washington and Baghdad have sent envoys to Pakistan to try to get Islamabad's support at the United Nations for a resolution that could pave the way for war with Iraq. 

On Sunday, Pakistan's right wing religious groups plan to hold anti-war demonstrations in Karachi and again on March 9 in Rawalpindi. 

In recent days, Karachi has been battered by violent, religiously motivated attacks. Last weekend, nine Shiite Muslims were gunned down outside their mosque in Karachi. On Thursday in two separate shooting incidents, two Iranian Shiite Muslims were killed by gunmen who sprayed their bakery with bullets and a Sunni Muslim cleric was shot and killed. 

The funerals of the two Iranians in Karachi erupted into violence when angry Shiite mourners pelted police with stones, ransacked vehicles and smashed shop windows. Police arrested 42 mourners. 

Outlawed Sunni Muslim extremist groups are suspected in the attacks on Shiites. Militant groups from each sect have surfaced in Pakistan in recent years.