HOUSTON (AP) - Authorities say a man believed to be the father of a patient has taken at least two people hostage at a hospital near Houston. It was not immediately clear if the man was armed.

The Harris County Sheriff's Office said Saturday night it believed the man was a distraught parent of a patient and at least two people were being held hostage at the Tomball Regional Medical Center. A supervisor at the county's emergency dispatch center said the situation was in the critical care unit and began around 7 p.m.

The hospital is on a 150-acre campus about 30 miles northwest of Houston.

Police in Tomball did not immediately respond to a message. No other information was immediately available.