It was not immediately clear if the church was holding services at the time of the shooting.
The community of Sutherland Springs, where the population numbers in the hundreds, is a small unincorporated area in Wilson County approximately 30 miles southeast of San Antonio. Amanda Mosel, who said her 13-year-old goddaughter died in the shooting, said about 50 people usually attend services. The official toll has not yet been verified by law enforcement or local officials.
It is unclear if the shooter was killed by police or took his own life, Mr Murphy said. Annabelle "was one very handsome, special child", Pomeroy told ABC News by phone.
The officials - one a USA official and the other in law enforcement - spoke to The Associated Press on the condition of anonymity because they weren't authorized to discuss the ongoing investigation, which they were briefed on.
May God be w/ the people of Sutherland Springs, Texas. He said he is on his way to Sutherland Springs to meet with families, local, state and federal officials.
One of the victims of the mass shooting was the church's pastor Frank Pomeroy's daughter, Annabelle.
U.S. President Donald Trump, now in Japan, tweeted to say that the FBI was investigating the shooting.
Special agents from ATF's Houston Field Division, San Antonio Field Office are responding to the scene of the shooting.
"From what I've heard, someone just walked in and started shooting", she said. Abbott's communications director tweeted that the governor is headed to Sutherland Springs for a briefing and media availability. "I am monitoring the situation from Japan".
Emergency personnel quickly rushed to the scene, with some victims evacuated by helicopter.