CAIRO (AP) — Deadly clashes broke out Saturday in Libya's capital between militias backed by its two rival administrations, portending a return to violence amid a long political stalemate.

At least 13 civilians were killed and over 95 wounded, the Health Ministry said. It added that 64 families were evacuated from areas around the fighting.

The escalation threatens to shatter the relative calm Libya has enjoyed for most of the past two years. The oil-rich nation plunged into chaos following a NATO-backed uprising that toppled and killed longtime autocrat Moammar Gadhafi in 2011.

Among the fatalities was Mustafa Baraka, a comedian known for his social media videos mocking militias and corruption. Baraka died after he was shot in his chest, according to Malek Merset, an emergency services spokesman.

Merset said emergency services were still trying to evacuate wounded and civilians trapped in the fighting that erupted overnight and continued into Saturday.

The Health Ministry said in a statement hospitals and medical centers in the capital were shelled, and ambulance teams were barred from evacuating civilians, in acts that “amount to war crimes.”

The municipal council of Tripoli blamed the ruling political class for the deteriorating situation in the capital, and urged the international community to “protect civilians in Libya.”

The violence caused widespread panic among Tripoli residents. Footage circulated online showed houses, government facilities, and vehicles apparently damaged from the fighting. Other footage showed militia forces deploying and heavy fire being exchanged across the night sky.

The U.N. mission in Libya said the fighting involved “indiscriminate medium and heavy shelling in civilian-populated neighborhoods” of Tripoli.

The mission called for an immediate cease-fire, and for all parties in Libya to “refrain from using any form of hate speech and incitement to violence.”

The clashes pitted the Tripoli Revolutionaries’ Brigade militia, led by Haitham Tajouri, against another militia allied with Abdel-Ghani al-Kikli, an infamous warlord known as “Gheniwa,” according to local media.

Prime Minister Abdul Hamid Dbeibah’s government, which is based in Tripoli, claimed the clashes broke out when one militia fired at another.

The fighting, however, is highly likely part of ongoing power struggle between Dbeibah and his rival Prime Minister Fathy Bashagha who is operating from the coast city of Sirte.

Both Dbeibah and Bashagha are backed by militias, and the later was mobilizing in recent weeks to try to enter Tripoli to dislodge his rival.

An attempt in May by Bashagha to install his government in Tripoli triggered clashes that ended with his withdrawal from the capital.

U.S. ambassador to Libya Richard Norland urged for de-escalation “before things get worse” and for Libyan parties to agree on an early date for elections.