Police in a western Indian city defused an explosive device Wednesday, the 19th unexploded bomb found there in past two days.

The latest discovery came Wednesday morning in one of the markets in the port city of Surat, local police commissioner R.M.S. Brar said. Eighteen explosives were found a day earlier.

Police have warned people to avoid gathering in public places, leaving Surat a virtual ghost town as residents stayed at home and businesses closed, Brar said.

Twenty-two blasts ripped through the nearby city of Ahmadabad over the weekend, killing 42 people and wounding 183. Seven small blasts also hit Bangalore in the south, killing one person.

A little-known Islamic militant group calling itself the Indian Mujahideen took credit for Saturday's attack in Ahmadabad, though authorities believe the claim may be aimed at covering the tracks of a better-known group.

On Tuesday, authorities launched a massive manhunt in the Mumbai suburb of Navi Mumbai where investigators believe the bomb plots were hatched.

Authorities say four cars — two used in the Ahmadabad attack and two found in Surat — were stolen earlier in the month from that suburb, and believe the nondescript area was used as headquarters by the bombers to try to avoid detection.

Also, authorities are checking the computer of a 48-year-old American citizen living in Mumbai after an e-mail claiming responsibility for an attack was sent from it.

Police say the man is not a suspect and they believe unknown attackers accessed his wireless internet connection.

India has been plagued by bombings in recent years, with almost all blamed on Islamic militants allegedly wanting to provoke violence between the Hindu majority and Muslim minority.

The country has suffered periodic spasms of sectarian violence since it gained independence from Britain in 1947 as the subcontinent was partitioned between a mainly Hindu India and a mainly Muslim Pakistan.

With files from the Associated Press