Two passengers on a United Airlines Boeing 757 flight from Newark to San Francisco were injured when the pilots responded to an onboard midair collision system warning, the Federal Aviation Administration said.

An United flight bound for San Francisco International Airport had to suddenly slow its descent to avoid another aircraft last week, leading to the hospitalization of two passengers, the airline said Tuesday.

The San Francisco-bound plane was alerted near Oakland, Calif., that another aircraft was in the vicinity, but it was able to land safely. The FAA is investigating.