Texas officials released the names of four volunteer firefighters on Sunday killed in a deadly blast in this close-knit Texas town, as authorities identified the center but not the cause of last week's deadly fertilizer plant blast.

Among the dead named at a news conference outside city hall in West, Texas, were brothers Doug and Robert Snokhous, remembered by their family as "lifelong best friends" who lived half a mile (800 meters) from each other and worked together at an ironworks in nearby Waco.

"Doug and Robert could always be seen together, whether they were hunting, working on cars, golfing or cooking barbecue at the volunteer fire departments cook-off," their family said in a statement read to reporters.

"They were always together and we were always comforted that they were together at the end."

The brothers were among 14 people, nearly all of them emergency responders, killed when a blast on Wednesday flattened the fertilizer plant and smashed several blocks of the small town, about 80 miles (128 km) south of Dallas. They are survived by their wives, children and grandchildren.

A liaison official for the Texas Line of Duty Death Task Force, which cares for the families of fallen first responders, read a statement for Dane and Rhonda Chapman, whose son Jerry Chapman died in the blast.

The Chapmans - who stood silently, their heads bowed - remembered him as man who had "found his passion and life." His faith in God and his fellow firefighters "gave him the strength to lay down his life for others," they said.

Officials identified a fourth firefighter, Kevin Sanders. His family said he gave his life protecting others, adding simply: "We love him and will miss him very much."

The explosion at the privately owned West Fertilizer Co retail facility gutted a 50-unit apartment complex, demolished about 50 houses and battered a nursing home and several schools. Dozens more homes were reported damaged.

A reporter allowed into the evacuated blast zone on Sunday said the roof was torn off the apartment complex. Large chunks of concrete hurled from the plant littered the complex grounds hundreds of yards (meters) away, and a basketball court was unrecognizable except for the toppled goals, according to a pool report.

"This is like a war zone," said Brian Hoback, a national response team investigator for U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, among more than 60 federal and state personnel working at the scene.

Assistant State Fire Marshal Kelly Kistner said a probe had identified a "large crater at the seat" of the blast, but neither its cause nor the location of the fire that preceded it have been determined.

Authorities have said there was no indication of foul play at the plant, which was last inspected for safety in 2011, according to a risk management plan filed with the federal Environmental Protection Agency.

Officials said the death toll remained at 14. McLennan County Sheriff Parnell McNamara said he did not know of anyone still unaccounted for, despite persistent rumors.

Matt Cawthon, chief deputy sheriff for McLennan County, said two of the dead were near or in the apartment complex. He was unable to give their age or gender.

A male resident from the nursing home died en route to the hospital after being evacuated, although it appeared his death was not directly caused by the blast, Cawthon said.

Memories of Trauma

An elementary school in the town is due to reopen on Monday, with additional temporary classrooms for students from another local school closed since the blast.

Officials announced a memorial service would be held for the first responders on the Baylor University campus in Waco, about 20 miles (32 km) to the south, at 2 p.m. CDT (3 p.m. EDT) on Thursday.

As the probe into the blast continued, hundreds of residents of the town, known locally for its Czech heritage, sought healing at church services on Sunday.

About 200 people - including farmers, military veterans and migrant workers - packed into the Church of the Assumption in the center of the town for Catholic mass.

Father Boniface Onjefu offered prayers for the 14 dead and nearly 200 injured in the blast, urging the congregation to "be strong and move our beloved city ahead. God is with us."

Larry Kaska, who lost his home on the north side of town, said the mass led by Onjefu brought "some healing" to residents as they started to rebuild their shattered lives.

"We're turning ... getting back to some normalcy again," said Kaska, who is now living at his nephew's home. "Just hearing his prayers and comfort, and (knowing) that people are being supportive ... help you out."

But for some at the church service, it was too early to speak of healing. Among them was Silvestre Duran, a Mexican migrant whose wife, Lucy, had suffered flashbacks since being injured as the blast tore through the nursing home where she worked.

Her face was marked by burns, and she had multiple stitches in her right ear. Their daughter, who also worked at the nursing home, was injured in the explosion too.

"A lot of people have memories that will be with them for a long time," Silvestre said.

Another churchgoer, who identified himself only as a farmer who had lived in West all his life, was still struggling to come to terms with the toll on the town.

"I lost three of my best friends ... I should have been maybe there with" them, he said, clearly shaken. "I just consider myself and my family blessed ... If you don't have faith in the good Lord, you have nothing."