Houston, May 18 (PTI): A gunman opened fire at a high school in the US state of Texas on Friday, killing at least eight persons. The incident took place at Santa Fe High School in the city of the same name, located about 50 kilometres southeast of Houston.

An unidentified law enforcement officer was shot, but sources said he was "clipped" and was not seriously injured.

At least eight persons were killed in the gunfire, Houston Chronicle quoted federal and county law enforcement officials have confirmed.

One source said the gunman was a male, but could provide no further information. The shooter has been "arrested and secured," said Santa Fe HS Assistant Principal Cris Richardson.

Several other students as well as an officer have been injured in the shooting.

This is the third school shooting in the past seven days, and the 22nd since the beginning of the year in the US.

Junior Liberty Wheeler, 14, was in class when she heard five shots ring out near the art room. Her teacher told them to run toward the theatre department's storage room, where they hid for 45 minutes before being escorted outside by the SWAT team. "You could small the gunpowder that came from the gun," Wheeler recalled as she was escorted out of the building. "We were all scared because it was near us."

The University of Texas Medical Branch at Galveston is treating two patients, their conditions not yet being disclosed, said spokesman Raul Reyes. He said more patients are expected, including one currently being transported from the branch's League City hospital.

Reyes said a helicopter with at least one patient is on the way and more ambulances are expected. President Donald Trump expressed concern over the incident.

"School shooting in Texas. Early reports not looking good. God bless all!," he tweeted.