TRIPOLI, Libya (AP) — Helicopters attacked camps and strongholds of Islamist militias Monday in eastern Libya as part of a nearly three-week offensive by a renegade general, violence that killed at least 18 people and sent civilians fleeing in panic, authorities said.

Militiamen responded by firing rocket-propelled grenades and anti-aircraft guns at the attacking troops allied with Gen. Khalifa Hifter.