Swiss police are describing the raid as highly professional and worryingly violent.

Ten masked men, armed with machine guns and pistols, stormed the casino, breaking down the entrance door with a sledge hammer.

Witnesses among the 600 guests say they were ordered to lie on the floor, some were injured by being stepped on or hit by the robbers.

The gang emptied the casino's cash registers of hundreds of thousands of pounds, and tried to get into the casino's strong room by firing shots at the door, but were unable to break the lock.

It's thought the gang, who witnesses say spoke French, may have escaped to France, the border is just 200 metres from the casino.

Swiss and French police are now working together to track the gang down.

raid:抢劫

stormed:突袭

sledge hammer:大锤

witnesses:目击者

cash registers:收银柜

strong room:保险库

gang:团伙

track the gang down:追查这组犯罪团伙