At least 26 people have been killed and 20 others injured in a mass shooting inside a church in Sutherland Springs, in the US state of Texas.

The shooting took place on Sunday at the First Baptist Church in Wilson County during the 11:00am (17:00 GMT) service, officials told reporters.

Sergeant Robert Murphy of the Guadalupe County Sheriff's office confirmed to Al Jazeera that the attacker was deceased. Officials later told reporters that the suspected gunman was found in neighbouring Guadalupe County dead in his vehicle, but it was not yet clear whether he was killed or died from a self-inflicted wound.

Texas Governor Greg Abbott told reporters that at least 26 people had died. Those who were killed ranged in age from five to 72 years old, officials said.

Authorities added that 23 people were killed inside the church, two outside and one person died after being transferred to a hospital.

'Largest mass shooting in state history'

"As a state we are dealing with the largest mass shooting in our state's history," Abbott said.

Officials said they could not yet name the attacker, but described him as a young white male. They added that he was wearing a ballistic vest, dressed in all black and used an assault-type rifle.

Authorities said the suspected attacker entered the church just after 11:20am local time (17:20 GMT) and opened fire. He then fled the church after a local resident used his own rifle to engage with the assailant. He was then pursued by police until he crashed his vehicle and was later found dead.

US President Donald Trump tweeted shortly after the shooting, saying he was "monitoring the situation from Japan" where he has just started a 12-day tour of Asia.

He later called the shooting a "horrific attack".

Contacted by Al Jazeera, the Wilson County sheriff was not immediately available for comment.

Sutherland Springs is a small rural community about 55km outside of San Antonio, Texas.

Sunday's attack comes just a month after one of the deadliest mass shootings in US history, when 58-year-old Stephen Paddock killed at least 58 people and injured more than 500 others. Paddock subsequently killed himself.

The Mass Shooting Tracker watchdog has recorded at least 24 mass shootings this month and more than 300 so far this year in the US.