Cryptocurrency exchange app announced that it has suspended deposits and withdrawals due to “unauthorized activity” on some accounts.

“Earlier today a small number of users experienced unauthorized activity in their accounts. All funds are safe,” wrote in a Twitter thread on Monday. “In an abundance of caution, security on all accounts is being enhanced, requiring users to: Sign back into their App & Exchange accounts, Reset their 2FA.”

“This update will be rolled out to users progressively over the next few hours. Once complete, withdrawals will be re-enabled,” the company said in a tweet. “We understand this may be an inconvenience, but security comes first. Thank you for your support.”

According to the Los Angeles Times, several app users have reported on social media that their currency had vanished from their accounts in the past few days.

This comes shortly after secured naming rights to replace Staples as the title sponsor of the Los Angeles sports center last month.