Wilson County Sheriff Joe Tackitt told the local paper there have been "multiple casualties and fatalities" and the shooter has been "taken down".
The number of victims and the extent of their injuries was not immediately clear.
Sutherland Springs is 30 miles (48 kilometers) southeast of San Antonio.
On Oct. 1, Stephen Paddock opened fire on a country music festival in Las Vegas, killing 58 and injuring over 500.
A spokesman for Brooke Army Medical Center also confirmed to CNN that the facility has received patients from the shooting, but the spokesman didn't have a specific number.
Reports suggest up to 27 people have been killed at a church shooting in South Texas.
"Our prayers are with all who were harmed by this evil act. I am monitoring the situation from Japan".
Federal law enforcement swarmed the scene to offer assistance, including ATF investigators and members of the FBI's evidence collection team. He thanked law enforcement for their response. Some things that get reported by the media will later turn out to be wrong.
First responders converged on the church in the small town and helicopters are taking victims to hospitals.
During its Sunday morning worship service, a Southern Baptist church in rural Texas became America's latest mass shooting.
Sutherland Springs is an unincorporated community located on the old Spanish land grant of Manuel Tarin in northern Wilson County.