MUMBAI - Mumbai broke out into a riot of colours, with dances on the street, loud music and revelry as lakhs of people turned up to bid farewell to their beloved elephant-headed god Ganesh here Thursday.

The immersion of the Ganesh idols after the 10-day annual festival has started on a peaceful note and there were no reports of any untoward incidents, Mumbai Police said.

Municipal Corporation of Greater Mumbai (MCGM), the Indian Navy, Coast Guard, social organisations, political parties and public groups geared up to oversee the immersion of an estimated 100,000-plus big and small Ganesh idols.

The immersion processions that have started moving out and the ceremonies are expected to continue on till Friday morning.

Shortly after the prayers at the noon, hundreds of Ganesh idols were taken out in big and small processions from every nook and corner of the city.

They wound their way to one of the 88 specific immersion sites prepared by the MCGM, the main among them being the Chowpatty, Mahim, Prabhadevi, Juhu, Versova and Marve beaches.

In addition, there are several other immersion sites, including the Mithi river inside the Sanjay Gandhi National Park in Borivli, Aarey Milk Colony, several small lakes, ponds and wells.

As in 2008, this year too the MCGM has created 17 artificial ponds for immersion of small-sized Ganesh idols to help ease the pressure on the major immersion sites along the sea front.

Mumbai Police have deployed over 25,000 personnel to monitor the immersion ceremonies all over the city.

Besides the police, the Indian Navy has positioned relief teams at the sea fronts in Malad, Ghatkopar, Mankhurd, Worli and Colaba. It has also provided two teams of Naval divers at Chowpatty and Powai with the latest equipment.

Similarly, the Coast Guard has deployed a high speed vessel, an interceptor boat and one helicopter off Mumbai to ward off any potential security threat during the immersion.

By late Thursday, an estimated five million people are expected to join the immersion ceremonies across the city and suburbs. The day is a holiday in Maharashtra.

The MCGM has deployed 40,000 staffers to oversee the immersion arrangements, 56 motorboats at various locations, 500 lifeguards, and 6,000 volunteers. It has also set up 60 first aid centres, 52 ambulances, 12 mobile toilet complexes and 31 watch-towers at the sea fronts.

“From the 10,000-plus public associations (sarvajanik mandals), the idols range from the tallest - a 28-foot high idol of Lord Ganesh, installed in Ganesh Gully, Lalbaug in central Mumbai — to the tiniest - a mere three-foot tall idol installed by the Vikas Sarvajanik Ganeshotsav Mandal at Bhandup in northeast Mumbai,” Brihan-Mumbai Sarvajanik Ganeshotsav Samanvay Samiti vice-president N. Dahibhavkar told IANS.

This year, there are 120 large Ganesh idols in different parts of Mumbai, a decline of around 20 percent over last year on account of security reasons, the swine-flu and recession, he said.