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(CNN) — The suspect in a shooting at a Texas high school Wednesday is in custody, Arlington police said.

Detectives have started interviewing 18-year-old Timothy George Simpkins, who will be charged with three counts of aggravated assault with a deadly weapon, Assistant Police Chief Kevin Kolbye said.

The shooting at Timberview High School left four people injured. Among the four injured, two were shot and three were hospitalized.

All three of those hospitalized are expected to survive, Kolbye said. He said a male student who is in an intensive care unit is now out of surgery.

An adult male who is hospitalized is in good condition, and a female who may have been grazed by a bullet is expected to be released, Kolbye said.

He said about 1,700 students were at the school Wednesday, and all have left the building.

The first report of a shooting on the second floor of the school came in around 9:15 a.m. (10:15 a.m. ET), Arlington Mayor Jim Ross said.

Police said the shooting may have happened after a fight between a student and another person during class.

Authorities started a “methodical search” and worked with several local police departments and the Bureau of Alcohol, Tobacco, Firearms and Explosives, Arlington police tweeted.

The department tweeted a photo of Simpkins and asked for the public’s help in finding him.

By early Wednesday afternoon, Simpkins was in custody.

Arlington police said a weapon was recovered in “the streets of Grand Prairie,” a few miles from the high school.

Grand Prairie police said the weapon recovered was a .45 caliber handgun.

Chief Daniel Scesney said police believe it was the weapon used in the school shooting, but that has not been confirmed. He said the gun has been turned over to the ATF for ballistics testing.

Metal detectors are not used at Timberview High School, which is part of the Mansfield Independent School District, a Mansfield ISD spokesperson said.