AP) — California is rolling out a voluntary smartphone tool to alert people if they spent time near someone who tests positive for the coronavirus as cases and hospitalizations soar throughout the state. People can opt into the new tool that Gov. Gavin announced starting Thursday. Officials say the tool doesn't track people's identities or locations. It uses Bluetooth wireless signals to detect when two phones are within 6 feet of each other for at least 15 minutes. At least 16 other states are using the system co-created by Apple and Google. Most residents of those places aren't using it.