CHANNELVIEW, Texas -

Security was heightened at all Channelview ISD schools Monday after five of its students were injured in an off-campus shooting over the weekend.

District officials confirmed that all five people shot at Johnson Place Mobile Home Community Sunday were students at Channelview High School.

"It's a sad thing you know," student Eric Herrada said.  "This close to the community where I go to school."

Harris County Sheriff's Deputies still don't know who shot at who - or why - but when it was over, a truck carrying several teenagers was riddled with shotgun pellets.

"It was like boom, boom, boom, real loud," one witness said.  Deputies also said they found evidence that a handgun was used as well.

"They started exchanging gunshots and my son did get shot in the face," Elma Flores said of her 17 year old son.  "There were windows blown out and there was blood."

Four people were transported to East Houston Regional Medical Center.  The other was taken by LifeFlight to Memorial Hermann Hospital in critical condition.  On Monday, his condition was upgraded to stable, deputies said.

Channelview ISD Public Relations Officer Mark Kramer said, "Our thoughts and prayers go out to all involved in this tragic event. We are working with t he Harris County Sheriff's Office during the course of its investigation."

Kramer added that as a precaution, all of its 13 campuses would remain on heightened security throughout the rest of the week.

Deputies said the investigation is still on-going but they do not believe a shooter is still on the loose.