At least 26 people are dead after a gunman opened fire inside a Texas church on Sunday morning, officials say.

The shooting occurred at the First Baptist Church in Sutherland Springs, approximately 30 miles from San Antonio, around 11:30 a.m. The shooter, who is believed to have acted alone, fled the church on foot and was killed by police, officials said. Police told reporters that the victims range in age from 5 to 72, with approximately 20 wounded being treated at area hospitals.

The shooter has been identified as Devin Patrick Kelley, 26, of nearby New Braunfels, Texas. Kelley was married and his mother-in-law listed a P.O. box in Sutherland Springs as a mailing address. His LinkedIn describes him as serving in the U.S. Air Force from 2009 until 2013, after which he briefly taught at a summer Bible school. Days before the shooting, he posted a picture of an assault weapon on Facebook with the caption: “She’s a bad bitch.”

One witness told a KSAT reporter the he was dressed “in full gear.” During a press conference in Sutherland Springs, state and local officials said that Kelley had an “assault-type” rifle and first fired outside the church before entering the building. An armed citizen pursued Kelley by vehicle after he left the church.

Whatever the final death toll, it is already the deadliest shooting at a place of worship in modern American history, surpassing the nine killed at Emanuel AME Baptist Church in Charleston, South Carolina in 2015.

At least six helicopters transported injured people to hospitals, the Dallas Morning News reported. At least four children, all from the same family, were wounded, CBS News’ David Begnaud reports.

Families gathered at the church, waiting for word from loved ones who had attended service that morning. One group held hands outside and prayed to God to “be with us as we learn to deal with this in days to come.”

Witnesses reported hearing up to 50 shots. Carrie Matula, who works near the church, told MSNBC that the shots sounded like “semiautomatic gunfire.”

Sutherland Springs is a small community outside San Antonio, with fewer than 1,000 residents.

“I never thought it would happen here,” Matula said. “This is something that happens in a big city. I would never have thought this would have taken place here. It’s just too tight a community. It doesn’t make sense.”

Texas Gov. Greg Abbott tweeted, “our prayers are with all who were harmed by this evil act. Our thanks to law enforcement for their response.” President Trump said he is monitoring the situation from Japan, on the beginning of his tour through Asia.

The Sunday shooting is Texas’ deadliest in modern history, surpassing a 1966 massacre at the University of Texas, Austin, when a shooter killed 15 and injured 31 others.