The US media quoted Wilson County Sheriff Joe Tackitt saying that 20 or more people were killed in the shooting.
The gunman was dead, said reports.
The shooting occurred in the First Baptist Church, which is a small county church.
The exact number of injured was not yet known.
Texas governor Greg Abbott tweeted: "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."
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