Newark Airport has reopened after it shut down Saturday due to an unknown emergency, according to airport officials. 

The airport said that a United plane made an emergency landing earlier in the day. Flights in and out of Newark were suspended momentarily, but flight activity has since resumed. The United flight was headed for Houston prior to its emergency landing.

The airport said to expect delays and to check with carriers before arriving at the airport. 

The Federal Aviation Administration's website said that arriving flights may be delayed an average of 1 hour and 36 minutes.