What should you do when the crossbuck sign at a railroad crossing has flashing red lights?

• Stop immediately, as a train is approaching
  Explanation:

  "At many crossings, the crossbuck sign has flashing red lights and bells. When the lights begin to flash, stop immediately! A train is approaching."
• Accelerate to clear the tracks quickly
• Proceed with caution, but be prepared to stop
• Ignore the flashing lights and proceed across the tracks