Washington, Apr 18 (EFE).- An explosion at a fertilizer plant in the town of West, Texas, near Waco, may have killed between five and 15 people, and wounded at least 179 others, a police spokesman said Thursday.

Between three and five firefighters are missing, Waco police spokesman Patrick Swanton told U.S. media outlets.

The blast at the West Fertilizer Plant in West, located about 20 kilometers (some 12 miles) north of Waco, occurred around 8:00 p.m. Wednesday and was heard up to 70 kilometers (43 miles) away, officials said.

The explosion leveled nearby houses and registered as a magnitude-2.1 seismic event on the U.S. Geological Survey's seismographs.

The blast occurred about 30 minutes after the fire department was notified that a blaze had started at the fertilizer plant, the police spokesman said.

About five or six blocks in the town were affected by the blast, with buildings sustaining extensive damage and officials concerned about residents' exposure to toxic fumes, West Mayor Tommy Muska said.

The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, or ATF, is assisting in the investigation of the blast, which occurred during a week that started with the explosion of two bombs near the finish line of the Boston Marathon. EFE