BEIRUT (AP) — A large explosion struck a Syrian intelligence building in the northern city of Aleppo on Wednesday, setting off heavy clashes between insurgents and government troops, two activist groups said.
The Aleppo Media Center and the Britain-based Syrian Observatory for Human Rights said the massive blast hit a branch of the Air Force Intelligence in the Zahra district on the western edge of the city. Air Force Intelligence is one of the most feared security services in the country.
The Observatory said the assault began with the rebels detonating explosives placed in a tunnel dug under the security branch. Rebels have used similar tunnel bombs in the past.
"Part of the building was destroyed. This was a very big explosion. People very far away could hear it," Observatory director Rami Abdurrahman said. "Clashes are still taking place. The Syrian regime is hitting the area with airstrikes."
He said there were heavy casualties on both sides in the attack, which was led by the al-Qaida-affiliated Nusra Front and other radical Islamic armed factions. There was no information from Syrian state media about the blast.