PORTLAND, Ore. - At least three structure fires tested firefighters in the Portland metropolitan area Wednesday, while another batch of firefighters tried their hands at tunnel rescues near the Columbia River. KATU has the rundown:

Fire in Hillsboro
Automatic sprinklers slowed a one-alarm fire that damaged a Hillsboro printing business Tuesday night. Advantage Press and Copy at 21440 N.W. Nicholas Court was closed at the time, and no one was injured.

Firefighters forced entry to the metal-clad building and found smoke to the floor. The fire was reportedly under control in 20 minutes. Crews remained on scene for another hour removing water from the business. 

Hillsboro Fire Investigators examined the fire scene, interviewed witnesses and determined the cause to be an oscillating fan that malfunctioned. The fan's motor apparently failed and ignited the plastic housing. The flames then extended to nearby shelving containing paper products and ended up causing an estimated $10,000 worth of damage. 

Firefighters say damage to the business would have been much worse without the aid of the building's automatic fire sprinkler system. No word as to how much damage was caused to paper products as a result of the sprinkers. More on this story, plus safety tips.

Fire in Gresham
KATU News captured video of a Wednesday morning mobile-home fire in the 2900 block of Northeast Division Street. Two responders from the American Red Cross' Oregon Trail Chapter assisted. The are providing lodging, food and clothing for the adult who escaped the mobile home fire with her pet dog.

There were no reported injuries. KATU News will follow with updates.

Fire in Southwest Portland
Fire investigators in Southwest Portland tell KATU reporter Valerie Hurst that a chimney fire nearly destroyed the home of a family of four. All four escaped the home safely.

It was the mother that roused her husband, teenage daughter and 11-year-old son and got them out of the house. out of the house, she hadn't realized how bad the fire was about to get. The fire, which started on the right side of the home where the stove pipe chimney is located, eventually spread over to the roof.

The fire broke out at about 2 a.m. after the family started a fire in the fireplace and went to bed. The family also told investigators it had been a while since the chimney had been cleaned.

Just testing
Meanwhile, Portland Fire & Rescue are running drills for trench rescues off Northeast Marine Drive near 122nd Avenue through Friday. The drills are with the Portland Water Bureau and the Portland Maintenance Bureau, practicing skills to "save workers in the event of a trench collapse," according to a Portland Fire & Rescue press release.

According to the release, "working on infra-structure below ground can be a dangerous job. The soils in many parts of Portland can be unstable and subject to cave-ins. Steps need to be taken to support the walls of a trench while people are preforming work deep inside."

When trenches collapse, and when people are trapped in the dirt or under the dirt, firefighters often are called to perform the "technical rescue."

More trench-rescue drill pictures.