The newspaper said Munoz, who is 56 years old, is currently being treated in a Chicago hospital.

The airline (UAL) released the following statement Friday afternoon:

We have been informed by Oscar’s family that he was admitted to the hospital on Thursday and we will provide further details as appropriate. In the meantime, we are continuing to operate normally.

Our thoughts and prayers are with his family and we are respecting their privacy.

United directors are waiting to hear back from his family and his doctors about the severity of the heart attack, the Journal reported. They hope to find out the information within the next 24 hours, the newspaper said citing a source, and then decide whether the big airline needs an interim leader.

Munoz was named President and Chief Executive Officer of United Airlines on Sept. 8 following the abrupt ouster of Jeff Smisek.

United is the world’s second-largest airline by traffic and is due to report its third-quarter 2015 financial results on Thursday, Oct. 22.