At least 26 people were killed and 27 injured in a mass shooting at a Texas church this morning, a law enforcement official told ABC News.

The alleged shooter, who has not been identified, is dead, and there is no longer an active threat at the First Baptist Church in Sutherland Springs, about 40 miles southeast of San Antonio, authorities said.

14-year-old girl among the victims

Among those killed at the white clapboard church was a 14-year-old girl named Annabelle Renee Pomeroy, according to her father, Frank Pomeroy, who is pastor at the church.

Annabelle “was one very beautiful, special child,” Pomeroy told ABC News by phone.

Pomeroy said he was in Oklahoma this morning -- a rare weekend that he wasn't at the church.

The other victims are all close friends of his, he said.

'We heard several shots and we all started running'

A woman who said she works at a gas station across the street from the church told ABC News she heard rapid gunfire at around 11:15 a.m. as congregants from the church as well as customers at the station ran inside the station for cover.

“We heard several shots and we all started running inside the store,” said the woman, who said she is 49 but declined to give her name.

“It lasted about 15 seconds," she said. "I yelled, ‘Get down! Get inside!’ and we all went into hiding.”

Within minutes of the gunfire, emergency personnel arrived at the scene, she said.

She said the gas station locked its doors and has not reopened.

Gathered at the scene, waiting for news

Police formed a perimeter around the church and flooded its grounds with emergency and police vehicles, according to ABC affiliate KSAT-TV in San Antonio.

The First Baptist Church is an unassuming, white structure with a red-hued door, with numerous flags in front, including an American flag and one for the Lone Star State. It’s on what appears to be a dusty road in a rural area.

A small group of people were seen clustered together outside the church, holding hands and attemping to pray, a KSAT-TV reporter said.

Agents from the FBI and ATF have responded to the scene.

At this point, today's church massacre is the fourth deadliest mass shooting in recent U.S history, falling after Las Vegas, Orlando and Virginia Tech.

President Donald Trump tweeted on the shooting from Japan, his current stop on his Asia tour. "May God be w/ the people of Sutherland Springs, Texas. The FBI & law enforcement are on the scene. I am monitoring the situation from Japan."

Texas Gov. Abbott said in a statement, "While the details of this horrific act are still under investigation, Cecilia and I want to send our sincerest thoughts and prayers to all those who have been affected by this evil act. I want to thank law enforcement for their response and ask that all Texans pray for the Sutherland Springs community during this time of mourning and loss."

Texas Attorney General Ken Paxton said in a statement, "The thoughts and prayers of all Texans are with the people of Sutherland Springs as tragic reports come out of First Baptist Church."

"Please join Angela and me as we pray for those impacted by this horrific shooting,” Paxton said.