Two women and two girls were killed late on Tuesday when a shell landed on a beach near Mitiga airport in the Libyan capital, Tripoli, officials said.
The shell also wounded 15 people, hospital official Mohamed Ben Khalil told Libya Al-Ahrar channel.
Pictures posted on social media showed plastic furniture strewn on the sand under strings of outdoor lights.
“The casualties are the result of clashes on Tuesday between a security force and outlaws who fired a shell that fell on a beach in front of Mitiga airport,” Abdulsalam Ashour, a deputy interior minister in Libya’s UN-backed government, told Al-Ahrar.
Other reports said the shell was fired during a revenge attack against one of the capital’s many armed factions.
Tripoli is home to a patchwork of armed groups, some of which share control of Mitiga and the surrounding area.
They occasionally clash in turf wars and localized disputes.
The beach lies across the other side of a coastal road from the airport in central Tripoli.
It is popular with families trying to escape the heat on summer evenings.