Some 200 sirens wailed at 6:24 p.m. (1254 GMT), the exact moment last Tuesday when the first of eight bombs tore through the city's commuter rail network. More than 200 people were killed and another 800 injured.
For two minutes or so, trains stopped running and cars paused on the city's usually gridlocked streets, while no planes took off or landed at Bombay's airport.
On sidewalks and street corners, large crowds gathered with bowed heads, unmoving and silent.
"I don't know anyone who died," said Rattan Phalli, 24, who joined hundreds of others, including President A.P.J. Qualm, at the railway station in suburban Maim — one of the blast sites — to pay tribute to those who lost their lives. "But tomorrow it could be me, or someone I know," she said.
At the airport, travelers described an eerily silent scene.
"People just stopped what they were doing," said Praia Thicker, who was flying from Bombay to New Delhi.
The minutes of silence came as the death toll from the July 11 attacks rose to 207, with officials adding to the total the victims who died after being taken to hospitals in Thane, a town just outside Bombay. "All of them are blast victims," said B.M Rut, a disaster management official in the state government of Maharashtra.
While police were still trying to determine who carried out the well-coordinated attacks, an outfit calling itself Lashkar-e-Qahhar said in an e-mail to a local television station that 16 people took part in the bombings in Bombay — also known as Mumbai — and that one was killed.
But "all the remaining 15 ... are totally safe, and celebrating the success of this mission and also preparing for the next mission," said the e-mail, written in poorly punctuated and often ungrammatical English.
"We also request all the Muslim brothers and sisters of India to (not) go near the main historical, governmental and the monumental places of India (especially in Delhi and Mumbai) in future," the e-mail said. "Otherwise, they get hurt too."
In the e-mail, a copy of which was provided to The Associated Press by Aaj Tak television, Lashkar-e-Qahhar said it would soon address doubts about its earlier claim of responsibility by providing audio and video proof.
Lashkar-e-Qahhar, or the Army of Terror, first took responsibility for the Bombay bombings in an e-mail Saturday to Aaj Tak, although investigators say they are still trying to verify the claim.
The group was unknown until it claimed responsibility for the March 7 bombings that killed at least 20 people in the Hindu holy city of Varanasi. Investigators believe it may be a front for Lashkar-e-Tayyaba, a Pakistan-based Islamic militant group that has long fought Indian rule in Kashmir, a predominantly Muslim Himalayan region.
Investigators were also hunting for leads in the northeastern state of Tripura, where they questioned two preachers from Tabliq-e-Jamaat, a legal Muslim organization, said Joint Commissioner of Police K.P. Raghuvanshi, who is leading the investigation into the attacks. He spoke from Bombay.
The preachers have spent the past three weeks in Tripura, delivering sermons in remote villages along India's porous border with Bangladesh. Authorities fear Muslim militants might be smuggling weapons and munitions across the frontier into India.
On Monday, authorities announced that the powerful military explosive RDX, often used by Islamic militants in Kashmir, especially Lashkar e-Tayyaba, was used in the July 11 attack.
Kashmir is divided between nuclear-armed neighbors India and Pakistan, but claimed in entirety by both. It lies at the heart of their long rivalry.
Several rebel groups have been fighting since 1989 to end largely Hindu India's rule over two-thirds of the territory.
India accuses Muslim-majority Pakistan of materially aiding the rebels, a charge Islamabad denies.
India's suspicions of a Pakistan link to the Bombay bombings have prompted New Delhi to slow a two-year peace process with its archrival.