One man operating in Chicago was arrested when police officers found marijuana and an unlicensed loaded firearm in his vehicle. CNN Money reports that the officers discovered the illegal items when the driver had been pulled over for not wearing a seatbelt. The man had two prior felony convictions, both of which were weapons-related, in 1995 and 2003. Neither of those convictions would have kept the driver from working for Uber since the company only bans drivers for felonies that have taken place within the past seven years, a stricter criteria than the one used to grant a taxi license in the state of Illinois.

The second Uber driver was arrested in Palo Alto, California. The man had picked up a female passenger and, after she had rejected his unwelcome advances, police say he refused to stop the car and let her out. He has been charged with sexual assault.

A spokesperson for Uber told Fortune that both drivers had only recently joined the app after being pre-screened and going through background checks. Neither of them had received any complaints “of this nature” up until this weekend, and both of the men have since been banned from the service.

This isn’t the first time that Uber has had issues with security. Late last year a driver in Delhi had been sentenced to life in prison after he had been found guilty of raping a female passenger. Earlier this year another driver went on a shooting rampage while on duty in Kalamazoo, Michigan, killing six.