According to Harris County Sheriff Ed Gonzalez, deputies responded to the crash in the 22300 block of SH-249.
Authorities say an HCSO deputy was out of his patrol vehicle tending to a disabled vehicle when he noticed a vehicle rapidly approaching him. The female driver then hit the back of the patrol car, officials said.
Law enforcement says the woman of the striking vehicle was taken to a hospital in critical condition. The sheriff says that it appears the woman was possibly impaired and she was not wearing a seatbelt.
The deputy was uninjured, authorities said.
In a Saturday evening update, Sheriff Gonzalez said lanes, including northbound lanes reopened after being closed for about 1 to 1.5 hours.