A U.S. Embassy convoy came under fire in Sudan, Washington’s top diplomat said Tuesday as he stepped up efforts for a cease-fire between the country’s two top generals. Still, forces of the two rivals pounded each other for a fourth day with heavy weapons in the capital of Khartoum. The attack on the convoy in Khartoum, along with an assault on the EU envoy’s residence and the shelling of the Norwegian ambassador’s home, signaled a further descent into chaos in the fighting.

Millions of Sudanese in the capital and in other major cities have been hiding in their homes, caught in the crossfire as the two forces battle for control, with each general so far insisting he will crush the other. The convoy of clearly marked U.S. Embassy vehicles was attacked Monday, and preliminary reports link the assailants to the Rapid Support Forces, the paramilitary group battling Sudan’s military, U.S. Secretary of State Antony Blinken told reporters. Everyone in the convoy was safe, he said.