Open-source mapping software Mapbox said that the person responsible for an antisemitic label added to its maps on Thursday morning also “attempted several other hateful edits,” and that its security team is still working to determine the exact origin of the vandalism.

“Mapbox has a zero tolerance policy against hate speech and any malicious edits to our maps. This morning, the label of ‘New York City’ on our maps was vandalized. Within an hour, our team deleted and removed that information,” according to a Mapbox spokesperson. Mapbox did not say specifically what other edits the person attempted.

Starting around 5 a.m. ET, users of apps that rely on Mapbox’s software, including Snapchat, CitiBike, and Zillow, saw that New York City had been relabeled ‘Jewtropolis’ on these maps.

It appears that the vandalism was visible from about 5 a.m. ET to 9 a.m. ET. Snap was one of the first companies to comment on the issue, tweeting around 7 a.m. ET that it was working with Mapbox to get the issue fixed.

According to its website, the apps that use Mapbox’s software account for more than 420 million monthly users.

Mapbox CEO and founder Eric Gundersen told TechCrunch that the company uses more than 130 sources of data to build its maps, and uses a combination of AI and humans to check for incorrect labels.

“We’re constantly scanning for this [vandalism], and it’s an error on our part [to have missed it],” Gundersen told TechCrunch.

In its press statement, Mapbox said that its detection system “flags more than 70,000 map changes a day for human review.” Mapbox said that the vandalism was properly flagged by its detection systems and put into quarantine for human review. However, Mapbox cited an error on the part of the human reviewer that led to the Jewtropolis label going live.

We’ll update this story if Mapbox shares any further details.