Jalalabad, Afghanistan ? A thunderous explosion Friday at a construction company rocked Jalalabad, devastating the surrounding neighborhood and blacking out power to this eastern Afghan city. Up to 25 people were reported killed and 90 injured.

Military officers blamed terrorists. The province’s deputy governor said it may have been an accidental detonation of stored explosives. The cause was under investigation.

The 12:30 p.m. blast in the western section of Jalalabad, 70 miles east of Kabul, the Afghan capital, occurred at a maintenance facility of the Afghan Construction and Logistics Unit, founded as a nongovernmental service organization but now a private business.

The Jalalabad police chief, Haji Ajib Shah, and its military commander, Hazrat Ali, said initially that about a dozen people were killed. But Ali said the death toll from what he called a “tremendous explosion” would probably rise as seriously injured died in the hospital.

Friday night, government television said the toll stood at 25 dead.

The blast destroyed 50 homes and damaged 500 others, some as far as 500 yards away, said Mohammad Sultan, military commander for the district. A hole 20 yards across was blown in the ground, and the remains of the construction company building burned for hours.

The explosion took place a few hundred yards from the Doronta dam and damaged its hydroelectric system, knocking out power to the city.

Sultan, at the scene, said he believed an explosives-laden car was detonated in a basement garage of the building, and he blamed “al-Qaida and the Taliban, the enemies of Afghanistan.”

Another army officer at the scene, Maj. Abdul Qayoom Azimi, said he believed terrorists had assembled explosives in the building over time, and then either deliberately or accidentally set them off.

Azimi said authorities had received information that there would be an attempt to sabotage the dam and consequently had put extra security on it.

Earlier, the deputy governor of Jalalabad’s Nangarhar province, Mohammed Assef Qazi Zada, said explosives were stored at the site and the blast may have been an accident, the Afghan Islamic Press agency reported.

The company builds roads, among other projects.

The fear of terrorism by resurgent Taliban or al-Qaida members runs high in Nangarhar province and much of the rest of Afghanistan eight months after a U.S.-led military campaign brought down the Taliban government and crippled its allies of the al-Qaida terror network.

A series of incidents have put Afghan security forces on alert, including the unsolved assassination of the longtime Nangarhar governor and the capture of a would-be car bomber in Kabul. In April, the new Afghan defense minister, Mohammad Fahim, escaped injury when a bomb exploded near his convoy in Jalalabad. Five people were killed in that blast.

Nangarhar province is suspected of harboring fugitive Taliban figures and holdouts of the al-Qaida terrorist network, who could easily cross to and from the tribal lands of neighboring Pakistan. The province is also an important opium-production and smuggling area.