A Red Robin restaurant was evacuated and closed after 24 customers became sick due to high levels of carbon monoxide Friday night in south suburban Orland Park.

About 7:22 p.m., two dozen customers reported feeling sick and having headaches while dining at the restaurant, located at 15502 S. LaGrange Rd., according to the Orland Fire Protection District.

Fire officials were called to the restaurant and tested the atmosphere, which showed high levels of carbon monoxide with readings of 400 ppm, the fire district said.

Customers and employees were evacuated. Four people were taken to local hospitals and another 20 were treated by paramedics on scene, authorities said.

Firefighters monitored the HVAC units causing the problem while the restaurant was ventilated and inspected by the Village of Orland Park Building Department, authorities said.

The Red Robin was closed Friday night and remained closed pending repairs, authorities.