Qwest Arena in happier times.

An intruder entered Block 22 LLC's Qwest Arena, tipped over a forklift after driving it in circles and caused extensive damage to the floor of the venue in Boise, Idaho.

A security guard at the nearby Grove Hotel saw a woman leaving the arena at about 3 a.m. on 17 August, say police. She was bleeding from the right shoulder and is considered a person of interest in the case.

There was a "trail of blood leading away" from the site, says Bonnie Way Snider, Qwest Arena communications director. "We think alcohol was involved because there was a beer can at the scene of the crime." No estimates were available on damages to the forklift or the floor.

Police may file charges of unlawful entry and malicious injury to property if an apprehension occurs.

Managers were preparing the arena for boxing matches this week as part of the 2008 Western States Police and Fire Games taking place 16-23 August in Boise.

The arena seats 5,000 and is the home of the Idaho Steelheads class AA hockey team, the Boise Burn arena football team and the Idaho Stampede developmental-league basketball team.