Four people were confirmed killed and more than 200 were injured in a series of explosions at a munitions depot on Saturday near the Albanian capital Tirana - but there was concern that the number of dead and hurt may dramatically rise.
Local reports spoke of at least six deaths, including that of a child, in the blast in one of four depots in a compound at Gerdec, on the outskirts of the city.
"The number of victims in the depot is big. We don't have a complete report on the tragedy, but the first signs are extremely disconcerting. This is an extreme tragedy for us," Prime Minister Sali Berisha said at the scene.
It appeared that most of the injured were caught by the blast - heard 200 km away in the Macedonian capital Skopje and registered as an earthquake by seismographs in Strasbourg - outside the depot.
"We don't know the exact number of victims, but we fear the worst regarding the 63 employees in the depot," government spokeswoman Juela Mecani said.
Interior Minister Bujar Nishani said that police has established contact with a group of the employees who were trapped in one of the compound tunnels.
"They are not in danger, but are trapped in a tunnel which we can't reach because of the repeated explosions," he told reporters.
Many of the injured were driving along the nearby Tirana-Durres highway. The power of the blast shattered most of the windows at Tirana's Mother Teresa airport.
The airport was briefly closed for a check of the navigation and communication equipment.
Residents in the area had to be evacuated as the explosions in the depot continued and ordnance was strewn far beyond the depot's two-kilometre perimeter.
Yet, hundreds of people were reportedly still in the danger zone late Saturday evening, afraid to move as the explosions continued to go off throughout the area.
Outside the four-kilometre "red zone" guarded by police, thousands of people frantically searched for relatives.
Mecani said that US military personnel were also at the site, which was being prepared for decommission. It is believed that mishandling of the ordnance - some of it stored there since World War II - triggered the blasts.
It was reported that a US company was commissioned to clean out the old storages and deactivate the ordnance.
Albanian authorities continued broadcasting appeals for blood donors and hundreds in Albania and in the neighbouring Kosovo rushed in response, reports said.