The Facebook-owned photo sharing service said Wednesday that criminals exploited a software bug that allowed them to access the accounts of an unspecified number of “high-profile” users.

Instagram did not say when exactly it discovered the data breach, only that it was recent. Hackers may have obtained the email addresses and phone numbers of some of the impacted users, but not their passwords, the company said. Additionally, Instagram said it fixed the software bug and is continuing to investigate what happened.

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“At this point we believe this effort was targeted at high-profile users so, out of an abundance of caution, we are notifying our verified account holders of this issue,” an Instagram spokesperson told Fortune in a statement.

Earlier this week, entertainment business publication Variety reported that the Instagram account of singer and actress Selena Gomez was hacked. Gomez’s Instagram account was then shut down after hackers posted nude photos of her ex-boyfriend and pop star Justin Bieber on Instagram

Eventually, Gomez’s account was restored after the photos were removed.

Instagram did not say if its recent data breach was related to Gomez’s hacked account and it did not reveal whose accounts were impacted.

“As always, we encourage people to be vigilant about the security of their account and exercise caution if they encounter any suspicious activity such as unrecognized incoming calls, texts and emails,” the spokesperson said.