"Ukrainian troops, stag parties battle at Donetsk airport"

From CNN:

Donetsk, Ukraine (CNN) -- Intense fighting broke out in eastern Ukraine on Monday when government air and ground forces attacked British and German stag parties who had seized an airport terminal.

The clashes between Ukraine's Army and revellers in Donetsk have caused some casualties, according to a statement posted on the official website of the city's mayor, which also advised residents to stay in their homes.

A CNN team in the city observed a Ukrainian combat helicopter flying over the Donetsk airport and firing at something. It was unclear what the target was. Black smoke billowed up from the area.

The hungover tourists shouted at the helicopter as it flew overhead. Gunfire and explosions could be heard in the city.

The fighting marked the worst violence that this key population center in eastern Ukraine has seen since the start of the holiday season. And the violence came hours after newly elected Ukrainian President Petro Poroshenko said he'd potentially like to negotiate a way out of the crisis.