Russia-Ukraine updates: US to ban Russian carriers from its airspace

Russia will begin negotiations again once "democratic order" is restored in Ukraine, Russian Minister of Foreign Affairs Sergey Lavrov said Friday, amid an ongoing invasion of the neighboring country.

"We are ready for negotiations, at any moment, as soon as the Armed Forces of Ukraine respond to the call of our president to cease resistance and lay down their arms. No one intends to attack them," Lavrov said during a televised meeting in Moscow with pro-Russian separatist leaders from eastern Ukraine.

Lavrov's comments come as Russian forces attacked Ukrainian troops in Kyiv on Friday morning, as the fighting drew closer to the capital's city center.

-ABC News' Anastasia Bagaeva and Patrick Reevell

Russia claimed Friday that its forces have so far disabled 118 elements of Ukraine's military infrastructure.

"These include 11 military airfields and 13 command and communication posts of the Ukrainian Armed Forces," Russian Ministry of Defense spokesman Igor Konashenkov said in a statement.

Konashenkov also alleged that more than 150 Ukrainian soldiers have "laid down their arms and surrendered during the fighting."

-ABC News' Anastasia Bagaeva

ABC News' team in Kyiv saw a large explosion and heard intense gunfire in the distance early Friday afternoon.

The crackles of gunfire appeared to be several miles north of the center of the Ukrainian capital, but still well within the city limits.

Ukrainian authorities have told residents in the northern suburb of Obolon to take shelter and prepare for imminent military action. The area is a 10-minute drive from Kyiv's center.

The capital remains on edge as Russian forces draw near. Earlier, Ukrainian troops were seen hurriedly moving with ammunition to set up positions in the city center as air-raid sirens rang out.

Thousands of people have tried to leave Kyiv and head west to the Polish border, with some spending hours stuck in long traffic jams.

The Ukrainian military said it has distributed 18,000 assault rifles to territorial defense volunteers in the capital. It has also begun handing out weapons to civilians who want to fight and has called on healthy men over the age 60 to join the defense force, if they wish.

-ABC News' Patrick Reevell

Ukraine's military claimed Friday to have killed an advance group of Russian saboteurs disguised as Ukrainian soldiers during a gunfight in the capital, Kyiv.

The Ukrainian military released video purportedly showing the bodies of men in Ukrainian uniforms and a destroyed truck. The fighting allegedly happened in an area only 10 minutes north of the city center.

Russian forces that crossed into Ukraine from the north on Thursday have been trying to advance south toward Kyiv. Fighting was taking place near a town 20 miles north of the entrance to the capital on Friday morning, ABC News has learned.

-ABC News' Patrick Reevell