HEATH, Texas (NEXSTAR) — A football coach in Heath, Texas, was placed on administrative leave after parents said he made their student-athletes do nearly 400 push-ups last Friday, which sent many players to the hospital.

In a letter to parents Tuesday, Rockwall-Heath High School Principal Todd Bradford confirmed that one of these school’s football coaches was placed on administrative leave following the incident that occurred during an eighth-period athletic class. Bradford said several students “needed medical attention, and in some cases, hospitalization.”

He also confirmed a third party is investigating the incident.

“To thoroughly investigate any connection between the activities in class and student illnesses, the district is retaining an independent third party to investigate the event,” the letter read. “The district is also taking interim action, including but not limited to, placing (the coach) on administrative leave while the investigation is pending and notifying appropriate outside agencies.”

The district also promised to provide support for the students involved.

One parent who wished to remain anonymous told the Dallas Morning News her son was hospitalized and diagnosed with rhabdomyolysis due to the intense workout. The mother said her son was forced to perform 300 to 400 push-ups without a water break, resulting in his hospitalization.

Rhabdomyolysis is a complex medical condition that can damage the heart and kidneys and, in some cases, lead to permanent disability and even death.

Two more Heath parents told the newspaper the students did more than 350 push-ups, with one parent saying the students had to perform the workout within a 60-minute timeframe.

Other Rockwall parents told the Morning News at least eight students were hospitalized based on conversations they had with other parents.