Students are escorted from Berrendo Middle School following an early morning shooting in Roswell, New Mexico, Jan 14, 2014. A shooter opened fire at a middle school in New Mexico on Tuesday, seriously wounding at least two teenage students before being taken into custody, police and hospital officials said. [Photo/Agencies]

HOUSTON - Investigators said Wednesday a 12-year-old boy planned the shooting rampage that injured two students at a middle school in the US state of New Mexico, local media reported.

New details about the shooting were revealed Wednesday as investigators garnered more evidence about the suspect one day after the tragedy alarmed the whole country. Investigators determined the shooting was premeditated and the two injured were chosen randomly as targets, local media KOB reported.

Though authorities have not officially released the suspect's name, local media identified him as Mason Campbell. Campbell opened fire Tuesday morning at Berrendo Middle School in New Mexico's southeastern city of Roswell, leaving two fellow classmates injured.

Police confirmed Wednesday the gun Campbell used was a 20 gauge pump shotgun that belonged to his parents and he had three rounds of ammunition, all expended in the shooting. He had reportedly warned some classmates to stay away moments before the gunfire rang out.

Campbell's family issued a statement Wednesday saying they were heartbroken and that their remorse could not be put into words.

"We are horribly sad over this tragedy on so many levels," the family stated. "We are praying that God will be with everyone who has been affected."

The family added it will cooperate with law enforcement to "piece together how this awful tragedy occurred."

The two victims, a 12-year-old boy and 13-year-old girl remained hospitalized Wednesday. The boy is listed in critical condition. Students who witnessed the shooting earlier told the media the suspect shot the boy twice in the face and shot the girl in the arm.

There was some confusion about the injured boy's age as some reports said the victim is 11.  His identity has not been released. The girl was later identified as Kendal Sanders by her father on Facebook.

A school staff member also suffered minor injuries when he stopped the shooter, New Mexico Governor Susana Martinez said at a press conference held on Tuesday afternoon.

The Governor said the shooter was  "quickly stopped by the staff member who walked right up to him and asked him to set down the firearm, which he did."  The shooting ended within seconds and did not escalate, according to Martinez.

The suspect has been taken into custody and police have reportedly searched his home. His motive of shooting remains unclear. Authorities have not provided any further details.