Multiple witnesses told CBS affiliate KENS that several people were shot at First Baptist Church in Sutherland Springs.
Wilson County Sheriff Joe Tackitt told the Wilson County News that a man entered the church and opened fire. Tackitt said there were multiple casualties and fatalities.
Wilson City Texas Commissioner Albert Gamez, Jr., told CBSN that he heard from an EMS official that 27 people are dead, but he said that number has not been confirmed.
Dana Fletcher, a business owner in the area, told CBS News she saw a "ton" of sheriff's vehicles and ambulances racing down the road. She said she doesn't know what happened but said there was heavy police presence and people were being airlifted from the scene.
The Connally Memorial Medical Center told CBS News it received multiple victims related to the shooting.
Video from KENS showed first responders at the scene, located about 30 miles southeast of San Antonio.
Special agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives said they were responding to the shooting.
A law enforcement official said an FBI crisis response team is on scene to offer assistance to local police, CBS News investigative producer Pat Milton reports.
The FBI will be offering evidence recovery, offering to check through databases to see whether this person has any connections to international terror to see if its a terrorist event or a domestic situation, Milton reports. She says officials looking into it but they don't know the motivation at this point.
Texas Gov. Greg Abbott tweeted his condolences to those affected in the incident.
"Our prayers are with all who were harmed by this evil act. Our thanks to law enforcement for their response. More details from DPS soon," Abbott tweeted Sunday.