Two passengers using the carpooling app Hitch were murdered in China in the past four months, prompting the government to suspend Hitch until better safety measures can be implemented.

Hitch is a carpooling service similar to Uber Pool run by Didi Chuxing, the most popular rideshare app in China. Didi Chuxing elbowed out Uber for the market in 2016 and has been growing ever since, with hundreds of millions of users.

In May, a Hitch driver allegedly stabbed his passenger, a 21-year-old female flight attendant, to death in the northern city of Zhengzhou. Then in August, a 20-year-old woman was allegedly raped and killed by her Hitch driver in the eastern city of Wenzhou. This crime was particularly alarming because the driver had been reported to Didi Chuxing by another user just the day before.

“Didi said another passenger had filed a complaint against the driver on Thursday, saying that the driver had asked multiple times for the passenger to sit next to him, took the passenger to a remote place and then followed the passenger after the person left the vehicle,” the New York Times reported at the time.

Didi Chuxing had already suspended service on Hitch in August following the second murder, but on Monday the China government ordered the app remain offline while it investigates further. The Ministry of Transport and the Ministry of Public Security issued a joint directive suspending the app and called on local governments to investigate all rideshare apps and reassess how drivers are screened.