Millions of passwords could be in the hands of hackers after app maker Trapster's website was compromised.
Around 10 million people use the app, which features information on speed traps and enforcement cameras.
"The Trapster team has recently learned that our website has been the target of a hacking attempt, and it is possible that your email address and password were compromised," said in a note to users.
"We have taken, and continue to take, preventative measures to avoid future incidents but we are recommending that you change your Trapster password."
Trapster has also set up an FAQ page to support its users. On the web page, the company said it would be best if account holders assume their email addresses and password were hacked.
"We therefore recommend changing the password on your account, and if you used that password on any other site, you should change your password on that site as well," the company said.
"This was a single event. We understand how it occurred, and have taken steps to help prevent it from happening again."
Trapster said it is not yet clear whether the hackers managed to successfully steal password or email data.
"We have nothing to suggest that this information has been used," the firm added.
"We have already rewritten the software code to help prevent this type of attack from happening again, and continue to implement additional security measures to further protect your data."
Last month, Gawker was hacked, potentially leaking millions of passwords.
Users were advised to change their login details and passwords for both Gawker sites and other online services.
