The two sides were scheduled to meet for a sixth round of negotiations on Sunday. Oman, which was set to host the talks, said on Saturday that this round had been canceled.

© Vahid Salemi/Associated Press

Maj. Gen. Mohammad Bagheri, the chief of staff of Iran’s armed forces, was among the dead, according to Iranian state media. Officials said a top nuclear negotiator was also killed.

The two powers have been exchanging barrages since Israel attacked Iran and killed many of the country’s top military leaders and scientists.

© Amit Elkayam for The New York Times