Using their night-vision equipment, U.S.-led coalition forces think they may have seen some of the escapees running in an open area near Bagram Air Field overnight.
Bagram District police chief Kabir Ahmad Rahyl confirmed that his men are searching nearby villages.
"Overnight, a signal was given to us in an area around the airfield," Rahyl said. "Two people were seen running away. It is not known whether they were the escapees or someone else. Our forces went immediately to the area. But we haven't found anything. So far, the houses [of nearby villagers] have not been searched. Only the orchards and gardens are being searched. If it is suspected that the escaped detainees may have been there, local police or Parwan Province police will search the houses."
The Reuters news agency reported today that one of the suspected militants had been captured at a mosque overnight. But Rahyl told RFE/RL the person apprehended at the mosque was not one of the suspects.
The Afghan security chief for Parwan Province, Brigadier General Maulana Abdulrahman Sayedkhaili, says he does not expect that foreign Al-Qaeda fighters would receive any sympathy from the local population around Bagram Air Field.
"I'm sure about the local people," Sayedkhaili said. "They are the enemies of terrorists [and supporters of the anti-Taliban commander Ahmad Shah Masood]. [Al-Qaeda] killed the champion of Afghan jihad, Ahmad Shah Masood. Therefore, anywhere the [escapees] are seen, the people will hand them over to the police."
A U.S. military spokesman, Lieutenant Colonel Jerry O'Hara, has described the four men as "dangerous enemy combatants." U.S. officials have refused to confirm the identities or nationalities of the escapees.
But Rahyl says his police officers have been given the names and home countries of the detainees, as well as photographs. He says all the men have beards and shaved heads and are wearing the orange jumpsuits of Bagram detainees.
"According to the reports that we have, four Arab detainees have escaped from Bagram Air Field," Rahyl said. "They are Abdullah Hashimi from Syria, Mahmood Ahmad Mohammad from Kuwait, Mohammad al- Fathani from Saudi Arabia, and Mohammad Hassan from Libya."
Marina Oven, a U.S. military spokeswoman at Bagram Air Field, told RFE/RL the detainees were discovered missing early yesterday when U.S. guards where taking a routine head count.
"We did have four detainees in Bagram and they are unaccounted for," Oven said. "And right now we are doing an extensive search. They were reported missing [yesterday] at about 5 a.m. And the search efforts began shortly thereafter."
Afghan truck drivers and construction workers often enter Bagram Air Field -- going through extensive security checks by U.S. soldiers at several checkpoints and gates along a two-kilometer stretch of road.
It is far easier for Afghan workers to leave the airfield -- either driving out in a vehicle or walking to the main gate along a dirt path that is separated from the roadway by coils of barbed wire.
RFE/RL correspondents have seen Afghan workers leaving through the main gate without being searched or asked for identification by U.S. soldiers or the Afghan troops that provide security at the airfield's outer perimeter.
However, the detention center where the escapees had been held is a high-security area within the airfield.
Lieutenant Colonel O'Hara said the U.S. military will conduct an internal investigation into how the detainees were able to get outside of that high-security area. The investigators are expected to determine whether the escapees received help from any guards or Afghan sympathizers within or near the airfield.
Hundreds of suspected militants have been held at the Bagram detention center since U.S.-led forces overthrew the Taliban regime in late 2001. They include senior members of Al-Qaeda who were arrested in Afghanistan and neighboring Pakistan, as well as suspected Taliban and Al-Qaeda fighters who since have been transferred to the U.S. detention center at Guantanamo Bay in Cuba.
About 450 suspected militants are currently being held at Bagram.
(RFE/RL Afghan Service correspondent Ahmad Hanaysh contributed to this report from Bagram; translations from Dari by Jan Alekozai in Prague.)