Three members of the Hamas (search) militant group were killed Sunday while handling explosives, Palestinian security sources said.

The men had pulled their car up alongside an abandoned vehicle used to store their explosives, and the storage vehicle blew up while one of the militants was handling materials inside, the sources said.

Witnesses said the men had rushed to scene after police attempted to clear out the area due to suspicions about the abandoned vehicle. They said the men were hastily trying to gather the explosives when the blast went off.

The security sources, speaking on condition of anonymity, said it was unclear whether the explosion had been accidental or whether Israel had carried it out.

Dozens of Palestinian militants (search) have been killed over the past 3 1/2 years of fighting while handling explosives meant for attacks against Israel.

Military officials, speaking on condition of anonymity, denied any army involvement in the incident.