UPDATE: Texas Town Grieves in Wake of Devastating Blast

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UPDATE:  40 people still missing
Searches resumed at a fertilizer plant early Friday after residents of the Texas town devastated by an explosion gathered to mourn their community's losses.

A non-denominational service was held at St. Mary of the Assumption Catholic Church on Thursday night. The Rev. Ed Karasek said that the town "will never be the same, but we will persevere."

He added: "Our hearts are hurting, our hearts are broken."

Officials have said as many as 15 people may have died and more than 160 others were injured in the blast, which occurred just before 8 p.m. local time (9 p.m. ET) Wednesday in the farming town of West a few miles north of Waco.

"The area around the site is just total devastation," Texas Attorney General Greg Abbott said at a news conference Thursday night. He said an apartment complex that was flattened "looks like it was a bombing site of an explosion the kind that you see in Baghdad."

Police initially said between five and 15 people may have been killed, and Mayor Tommy Muska, a member of the town's Fire Department, told NBC News that he feared those numbers could double. But state officials said it was too soon to say how many had died.

Despite the lack of official confirmation, The Associated Press reported that the names of the dead were becoming known in the town of 2,800.

"Word gets around quick in a small town," said local resident Brenda Covey, 46. 

Earlier, Sgt. Jason Reyes of the Texas Department of Public Safety said he could confirm that "we do have fatalities," but he refused to give any numbers.

"You've got to understand, we are still in a search-and-rescue mode right now," he said.

Tommy Muska, a volunteer firefighter and the mayor of West, Texas, which was rocked by an explosion at a fertilizer plant on Wednesday, talks about the search for survivors and how the town will move forward.

Matt Cawthon, chief deputy sheriff of McLennan County, said Thursday afternoon that the presence of dangerous chemicals at West Fertilizer Co., including ammonium nitrate, was significantly slowing the investigation.

Agents from the state Commission on Environmental Quality and the U.S. Environmental Protection Agency were combing the scene "to determine just how dangerous it is for our first responders," he said.

The cause of the fire and explosion remained undetermined, but there was no indication of criminal activity, Waco police Sgt. William Patrick Swanton said. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives said it was sending the same National Response Team that worked this week's explosion at the Boston Marathon to lead the Texas investigation. 

"We do not know the number of any fatalities. We do not know where the fire started. We do not know the cause," Assistant State Fire Marshal Kelly Kistner said.

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