UPDATE, 6:20 p.m.:  It appears that the fatality was intentional, Caltrain spokeswoman Tasha Bartholomew said.

UPDATE, 4:15 p.m.:  Trains are single-tracking at restricted speeds through the area where a person was fatally struck on the tracks in San Mateo this afternoon, according to Caltrain officials.

A commuter train struck and killed a person Tuesday afternoon in San Mateo, according to Caltrain officials.

The incident occurred around 2:35 p.m. on the Caltrain tracks near Bellevue Avenue, Caltrain officials said. The southbound train had about 700 passengers on board at the time.

Trains are being held in the area as emergency personnel respond to the scene.