A large explosion at the Falk Corp. plant rocked Milwaukee's Menomonee River Valley this morning, sending smoke and debris hundreds of feet into the air, killing at least two people and injuring many more.

Initial reports indicated that about 25 people were injured in the explosion and the ensuing fire, which engulfed two warehouses at about 8:07 a.m. The site is located near the intersection of Canal and 30th streets.

Milwaukee Mayor Tom Barrett said at least one person was missing in the wreckage, Barrett said.

Firefighters said they could see at least two bodies in the wreckage, according to a report at WTMJ-AM 620.

Witnesses said they believed the cause of the explosion involved some large propane tanks at the site, which is located just east of Miller Park on the city's near south side.

Linda Mayer, spokeswoman for Rexnord Corp., which acquired Falk Corp. in May 2005, said, "We are extremely concerned about the welfare of our employees."

The force of the blast was felt by people as far away as Racine County, Franklin, Muskego and General Mitchell International Airport.

The smoke from the blaze caused motorists to slow down and look at the fire, backing up traffic along Interstate 94.

The Sixth Street, 16th Street and 27th Street viaducts over the valley were closed, as were the nearby freeway exit ramps, to keep the public away from the site, Barrett said.

About 120 firefighters and paramedics responded to the five-alarm fire, which was extinguished by 10:30 a.m., Milwaukee Fire Chief William Wentlandt said.

Milwaukee Police Department spokeswoman Anne Schwartz said, "We are conducting a full police department investigation" into the explosion.

Miller Park became a staging area for emergency crews responding to the scene. Falk employees and family members were being tended to at the ballpark, according to Rick Schlesinger, executive vice president of the Milwaukee Brewers.

"This is certainly not something you plan for, and it's something you never have to do. Our thoughts are with the families," Schlesinger said.

Schlesinger told SBT he was at a business meeting near the site when the explosion occurred, and its impact was felt throughout the neighborhood and the ballpark.

"People said the explosion rattled windows and knocked things around in their offices. It was quite a blast," Schlesinger said.

Falk Corp. is a manufacturer of gears and couplings, with annual revenues of approximately $200 million. The company recently announced plans to add 90 jobs to its Menomonee River Valley plant.

Falk and Rexnord were acquired by Apollo Advisors L.P., a Purchase, N.Y.-based firm that specializes in buying distressed companies, earlier this year. Rexnord manufactures bearings, chains, couplings, drives, motor brakes, idlers and other parts for the power transmission industry.