Investigators Tuesday morning are hoping daylight can help them get a better idea of what caused a massive fire on two barges used to set off Plymouth’s Fourth of July fireworks display Monday night. Plymouth police confirmed on Twitter that a barge caught fire during the fireworks, and said another barge also had a malfunction.Witness Danielle Harrington was watching the display from a boat about 3/4 of a mile from the barge. She said about halfway through the show, something went wrong.