Waymo launched the next phase of its self-driving ride-hailing service in Phoenix today.

For now, only a few hundred people will have access to the Waymo One app and ride-hailing service, which will feature a safety driver during all rides. Vehicles will be available 24/7 and can be taken to several cities in the Phoenix metropolitan area, including Chandler, Tempe, Mesa, and Gilbert.

Riders will see a price estimate in the Waymo app before they request their ride.

Waymo officials said in a company blog post that they hope to make Waymo One available to more people as they add vehicles and service areas.

"There’s a long journey ahead, but we believe that Waymo One will make the roads safer and easier for everyone to navigate," Waymo's CEO John Krafcik wrote in a Medium post. 

Waymo will also continue its early rider program, which has been in operation in the Phoenix area since 2017. Unlike those who are part of the Waymo One program, early riders will be required to continually provide feedback to Waymo on their ride experiences. 

Waymo, owned by Google parent Alphabet Inc., is also currently working on expanding its autonomous vehicle testing California's Bay Area.