Russia’s Yandex Taxi had its ride-hailing app hacked earlier this week, leading to a massive traffic jam in Moscow. The hacktivist collective Anonymous has taken credit for the attack.

Hackread reports that hackers bypassed Yandex’s security mechanisms, creating multiple false orders for taxis and sending all available cars to the same location, the city’s Fili district, which is outside of Moscow‘s center and runs toward Kutuzovsky Prospekt.

A Yandex representative confirmed the cyberattack to Vice, saying that “On the morning of September 1, Yandex Taxi encountered an attempt by attackers to disrupt the service – several dozen drivers received bulk orders to the Fili district of Moscow.”

Read Also: Swarm Of Cruise Robotaxis Got Confused And Blocked Off A San Francisco Street

The spokesperson claimed that the issue had been cleared up in about an hour, a number more or less repeated by Forbes Russia. Anonymous, who say they were acting with the assistance of the IT Army of Ukraine, claim the traffic jam lasted more like three hours.

It’s unclear why the Fili district was targeted, but the jam happened along a busy thoroughfare, which likely made it inconvenient to a large number of people. The city is no stranger to traffic jams, though, and CBS News reported earlier this year that Moscow has the second-worst traffic on earth behind Istanbul, Turkey.

Although the hack appears to have amounted to little more than an inconvenience, it demonstrates how increasingly connected vehicles can be compromised remotely. Car hacking has become so prominent, in fact, that DEF CON, a hacking conference, has started hosting a Car Hacking Village.

Yandex Taxi, though, says it will be better protected against hackers going forward, as it told The Verge its “algorithm for detecting and preventing such attacks has already been improved to prevent similar incidents in the future”.