ARLINGTON, TEXAS -- A student opened fire at a Dallas-area school Monday morning, killing one student and injuring another before being arrested on a capital murder charge, police said.

The shooting began on a high school campus in the suburb of Arlington around 6:55 a.m., before many students arrived for the first day back to classes after the spring break, according to police and school district officials.

Arlington police Chief Al Jones said Monday that a male student who was shot died at a hospital and a female victim was receiving medical care after being "grazed" by shrapnel, causing injures that aren't life threatening. He declined to give their ages or grades.

Another male student was arrested at the scene and charged with capital murder, Jones said at an afternoon news conference. The police chief declined to identify the suspected shooter because he is a minor, but said he is being held at a juvenile detention center in the area.

The gunman ran from the scene without ever entering the Lamar High School building and was taken into custody by responding officers "within minutes," Jones said. He said investigators recovered a gun used in the shooting but the shooter's motive and where he got the weapon remain unclear.

Jones said the police officers normally stationed at the school weren't there during the shooting, which began shortly before the officers were set to start duty.

Arlington Independent School District spokeswoman Anita Foster said the school went into lockdown during the shooting but school buses and other arriving students were diverted from the campus before classes were set to begin. Police said they completed their search of the school at 10:40 a.m.

School staff began reuniting students who'd been sheltering inside the building with their parents or guardians around 11 a.m., according to Superintendent Marcelo Cavazos. He said there would be no classes Tuesday and counselors would be available to students and staff on Wednesday.

In Texas, people convicted of capital murder can be sentenced to death. Prosecutors make the ultimate decision about what charges to pursue in a case, and those are not always the same as the charges brought upon arrest.