Iraqi officials say Islamic State militants have destroyed a lock on the Euphrates River that served as a bridge in Ramadi as government forces close in on the militant-held city west of Baghdad.

Iraqi Maj Gen. Ismail al-Mahlawi, the head of military operations in the western Anbar province, said Wednesday that the lock was the last remaining bridge from the city center to the northwest. He says its destruction leaves some 300 ISIS fighters trapped in the center of the city, which the militants seized in May.

Iraqi forces backed by U.S.-led airstrikes pushed into Ramadi earlier this week, capturing a military complex north of the city and a neighborhood on its outskirts.