Less than a week until the referendum to decide the future of Ukraine’s southern Crimea region, unidentified armed men shot into the air as they moved into a Ukrainian naval post in Crimea, a Ukrainian defence official in the region was quoted as saying by local media.

Ukraine’s Channel 5 television quoted Vladislav Seleznyov as saying the shooting, a rare occurrence since pro-Russian forces took over the Black Sea peninsula a week ago, took place at a motor pool base near Bakhchisaray.

Yarik Alexandrov, one of the servicemen at the base, left after the confrontation. He said he refused to swear an oath to Russia:

“I don’t know,” said Alexandrov. “I was standing outside our barracks when they told us to surrender. We said we are not going to surrender. They started shooting under our feet. Then we surrendered. What else could we do? We didn’t have weapons or anything, so we surrendered. They told us to swear to serve Russia. Some people refused, the others said they would serve Russia, those (servicemen) from Crimea. I left the base.”

The base personnel appeared to be deeply divided: some serviceman wanted to join and serve for Russia, while others preferred to serve Ukraine.

The capture of the base comes as pro-Russian self defence groups continued to tighten their grip on the peninsula where several military installations were seized.