BEIRUT (AP) — Syrian opposition activists say airstrikes on rebel-held parts of the besieged city of Aleppo have killed at least eight people.

The activist-operated Aleppo Today TV station and Qasioun news agency say bunker-busting bombs were used in an attack on Tuesday on the Bustan al-Qasr neighborhood in eastern Aleppo.

Other activists groups and a member of the Aleppo local council, Zakaria Amino, say the death toll is likely to rise because the bombs fell in a number of neighborhoods. Amino says rescue workers are still searching for people under the rubble.

The opposition-held part of Aleppo has been under an intensive aerial campaign since last month after the collapse of a cease-fire that barely lasted a week. Syrian pro-government forces are also pressing a ground offensive into the rebel-held districts.