According to JetBlue, Flight 704 from San Juan to New York on Saturday evening was evacuated after the plane experienced engine trouble.
The flight with 186 passengers and 6 crew never took off because the pilots rejected take-off. The passengers were evacuated and put on another plane or given alternative options.
According to Carib News, firefighters suggest a heron got stuck in the engine which caused the failure.
Here is a picture of the plane from PR Plane Spotters. they have a lot more on Twitter if you want to check them out.