A Texas teenager was charged with assault after six students were hospitalized when they ate marijuana-laden brownies he served them at a school band practice, myFOXaustin.com reported Wednesday.

Kevin Coffey, a 17-year-old student at Austin's Lake Travis High School, told authorities he didn't know the brownies contained drugs when he handed them out -- but police said text messages he had sent to friends proved otherwise.

Police said many of the students were unaware of the brownies being laced with pot and six were transported to the hospital by their parents.

Doctors found high levels of THC (tetrahydrocannabinol, the active chemical in cannabis) in their system, but the seriousness of their sickness was not reported.