UPDATE 1-Indian commandos exchange fire with militants

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NEW DELHI, Nov 27 (Reuters) - Gunfire and explosions were heard from Mumbai's Taj Hotel on Thursday as Indian commandos took on Islamist militants holed up there, with smoke billowing from one open window, witnesses and TV channels reported.

At the nearby Trident-Oberoi Hotel, where scores of people were trapped and some taken hostage by militants, there was also a fresh round of firing, with television channels saying commandos had also entered the building.

At least three people were seen leaving the hotel's back door, television channels said.

Commandos had also gathered outside a Jewish centre where a rabbi is thought to have been taken hostage, but later apparently decided to hold off from an assault.