Ukraine unleashed one of its largest long-range drone bombardments of the war before dawn on Tuesday at targets across Russia, including dozens of strikes directed at the Moscow region, as both sides stepped up attacks ahead of talks intended to end three years of fighting.

The Russian Ministry of Defense claimed to have shot down 337 drones, with at least 91 sent toward the capital and the region around it.

Moscow’s mayor, Sergei Sobyanin, said the attack was the largest against the city since the start of the war. At least two people were killed and 14 more were injured, the Russian authorities said.

In Moscow, at least one residential building was damaged, with its roof charred, after a drone explosion. All four international airports, serving a metropolitan area of 21 million, were forced to suspend operations temporarily because of the attack, the country’s aviation watchdog said.

Ukraine has proposed an immediate truce in the air, saying it would immediately stop long-range strikes into Russia if Moscow agreed to an equivalent halt.

That plan, supported by European nations, including France, is envisioned as a first step in building trust ahead of talks about the overall conflict, in which over a million Ukrainian and Russian soldiers have been killed or injured.