Fertilizer plant explosion near Waco, Texas

Churchgoers pray after a First Baptist Church service held in a field because the building was in the damage zone after a massive explosion at a fertilizer plant in West, Texas.  (Charlie Riedel / Associated Press)

Volunteers Dub Harris and Virgil Thompson, right, both from Temple, Texas, cut lumber to build a ramp for a temporary classroom after an explosion at a fertilizer plant in West, Texas, damaged three of the district’s schools.   (Charlie Riedel / Associated Press)

Firefighters conduct a search-and-rescue mission at an apartment complex destroyed by an explosion at a fertilizer plant in West, Texas.  (LM Otero / Associated Press)

This apartment complex was destroyed by an explosion at a nearby fertilizer plant in West, Texas.  (LM Otero / Associated Press)

Firefighters set a brace to support a beam during a search-and-rescue operation at an apartment complex destroyed by an explosion at a fertilizer plant in West, Texas.  (LM Otero / Associated Press)

Merchandise and glass are scattered in the West Thrift Shop in West, Texas, on Thursday, a day after a massive explosion at the West Fertilizer Co.  (Paul Moseley / Associated Press)

Workers board up windows of a home near the site of the fertilizer plant explosion in West, Texas.   (Erich Schlegel / Getty Images)

Residents at the West Community Center pray for the victims of the explosion at the West Fertilizer Co.   (Chip Somodevilla / Getty Images)

West High School students Kelsey Hoelscher, left, and Heather Perry embrace after a prayer session for the victims of the fertilizer plant blast in West, Texas.   (Chip Somodevilla / Getty Images)

Texas Atty. Gen. Greg Abbott speaks to reporters about the massive explosion at a fertilizer plant that occurred in West, Texas.   (Frederic J. Brown / AFP/Getty Images)

Firefighters search an apartment destroyed by an explosion at a fertilizer plant in West, Texas.  (L.M. Otero / Associated Press)

A massive explosion at the West Fertilizer Co. killed as many as 15 people and injured more than 160, officials said overnight.   (L.M. Otero / Associated Press)

Firefighters conduct a search and rescue operation in the blast zone of an explosion at a fertilizer plant in West, Texas.  (L.M. Otero / Associated Press)

A firefighter handles a children’s bunk bed during a search of an apartment destroyed by an explosion at a fertilizer plant in West, Texas.  (L.M. Otero / Associated Press)

A victim from the West fertilizer plant explosion is wheeled into Hillcrest Baptist Medical Hospital in Waco, Texas.  (Jerry Larson / Associated Press)

Firefighters conduct search and rescue of an apartment destroyed by an explosion at a fertilizer plant in West, Texas.  (L.M. Otero / Associated Press)

The remains of the the West Fertilizer Co. plant smolder in the rain on Thursday in West, Texas.  (Smiley N. Pool / Associated Press)

Waco police spokesman William Swanton addresses the media during a press conference about the fertilizer plant that exploded in West, Texas.  (Larry W. Smith / EPA)

A cloud of smoke rises from a fertilizer plant where an explosion occurred in West, Texas.  (Andy Bartee / McClatchy-Tribune)

An injured person is assisted as a nursing home is evacuated after an explosion at a nearby fertilizer plant in West, Texas.   (Rod Aydelotte / Associated Press )

Emergency workers fight a house fire after an explosion at a nearby fertilizer plant in West, Texas.   (Rod Aydelotte / Associated Press)

Rescue workers pass a damaged apartment complex after an explosion at a fertilizer plant in West, Texas.  (Rod Aydelotte / Associated Press)

Emergency workers evacuate elderly residents from a damaged nursing home after an explosion at a fertilizer plant in West, Texas.   (Rod Aydelotte / Associated Press)