Three people have died after a vehicle hit four pedestrians on a sidewalk in Fountain Hills Tuesday morning, fire officials said.

A Rural Metro fire spokesperson confirmed two people were pronounced dead at the scene and two others were transported in extremely critical condition.

The Maricopa County Sheriff's Office said one of those transported later died.

"Fatalities are confirmed," according to a tweet from Maricopa County Sheriff's Office spokesperson Sgt. Joaquin Enriquez.

The pedestrians were two men and and two women in their 50s or 60s and the driver has been identified as 27-year-old Alex Bradshaw, according to MCSO.

He was headed north on Saguaro Boulevard when he veered off the road and hit the pedestrians on the corner of Saguaro and Palisades, MCSO said.

It's not clear how what caused the crash. An MCSO spokesperson said the driver stayed at the scene of the crash and showed no signs of DUI, but that doesn't mean he won't face charges.

Palisades Boulevard was closed in both directions between Saguaro and Avenue of the Fountains, MCSO said.

MCSO is investigating the crash.