India suspects two senior leaders of a banned Pakistani militant group orchestrated the three-day siege of the country's financial capital that killed at least 171 people, Indian officials said Thursday.

Evidence collected in the investigation pointed to Zaki-ur-Rehman Lakhvi and Yusuf Muzammil as masterminds behind last week's bloody rampage in Mumbai, according to two government officials familiar with the matter.

Lakhvi and Muzammil belong to outlawed Pakistani group Lashkar-e-Taiba — which India blames in the attack — and are believed to be living in Pakistan, the officials said. Lakhvi was identified as the group's operations chief and Muzammil as its operations chief in Kashmir and other parts of India.

The lone surviving gunman in the assault told police Lakhvi recruited him for the operation, and the assailants called Muzammil on a satellite phone after hijacking an Indian vessel en route to Mumbai. During the attacks, the gunmen used mobile phones taken from hotel guests to place calls to the Pakistani city of Lahore.

The Indian officials spoke on condition of anonymity because they weren't authorized to talk publicly discuss the details

The revelations added to the growing evidence linking the attacks to Pakistani-based militants, and came as U.S. Secretary of State Condoleezza Rice arrived in Pakistan on Thursday for meetings with civilian and military leaders after visiting India.

Rice aimed to increase pressure on Pakistan's government to share more intelligence and go after terrorist cells believed rooted in the country, saying that Pakistan must mount a "robust response" to find those responsible in the attacks.

U.S. Joint Chiefs of Staff Chairman Mike Mullen was pushing the same message in Pakistan on Wednesday, and also was to meet with officials in India during his trip.

Indian airports, meanwhile, were put on high alert after the government received warnings of possible airborne attacks.

"This is a warning which we have received. We are prepared as usual," India's air force chief, Fali Homi Major, told reporters Thursday.

Last week's attacks were carried out by 10 suspected Muslim militants against upscale hotels, a restaurant and other sites across Mumbai.

In a stunning new example of the botched security that has sparked public outrage since the assault, police on Wednesday found two bombs at Mumbai's main train station nearly a week after they were left there by the gunmen.

While searching through about 150 bags, which police believed were left by the dozens of victims in the Chhatrapati Shivaji Terminus station, an officer found a suspicious-looking bag and called the bomb squad, said Assistant Commissioner of Police Bapu Domre. Inside were two 8.8-pound (4-kilogram) bombs, which were taken away and safely detonated.

After the attacks, police found unexploded bombs at several of the sites, including two luxury hotels and a Jewish center.

It was not immediately clear why the bags at the station were not examined earlier. The station, which serves hundreds of thousands of commuters, was declared safe and reopened hours after the attack.

The discovery comes amid intense criticism that India's security forces missed warnings and bungled their response to the Nov. 26-29 attacks.

Fallout from the attacks widened Thursday as the chief minister of Maharashtra state, where Mumbai is located, stepped down after being pressured by the ruling Congress Party. The country's top law enforcement official resigned last week.

"I regret that we could not have saved more lives, that regret will remain with me," the minister, Vilasrao Deshmukh, told reporters.

With public anger over the attacks increasing by the day, Foreign Minister Pranab Mukherjee on Wednesday adopted a more strident tone against India's longtime rival, saying there's "no doubt" the assailants were Pakistani and their handlers in Pakistan.

"The government of India is determined to act decisively to protect Indian territorial integrity and the right of our citizens to a peaceful life, with all the means at our disposal," he said, a turnaround from earlier statements that ruled out military action.

Many Indians wanted more than just harsh words.

At a candlelight gathering in Mumbai, many chanted anti-Pakistan slogans and called for war.

"India should attack Pakistan right away," said Sandeep Ambili, 27, who works for a shipping company.

"Something has to be done. Pakistan has been attacking my country for a long time," said another protester, Rajat Sehgal. "If it means me going to war, I don't mind."

Similar rallies were held in cities across India.

After a 2001 militant attack on India's parliament, also blamed on elements in Pakistan, the two neighbors posted nearly 1 million soldiers along their border in a yearlong standoff. The two nations have fought three wars since independence from Britain in 1947, but neither government wants a fourth. Both now have nuclear weapons.

India has called on Pakistan to turn over 20 people who are "fugitives of Indian law" and wanted for questioning, but Pakistani President Asif Ali Zardari said the suspects would be tried in Pakistan if there is evidence of wrongdoing.

Much of the evidence that Pakistanis were behind the Mumbai attack comes from the interrogation of the surviving gunman, who told police that he and the other nine attackers had trained for months in camps in Pakistan operated by the banned militant group Lashkar-e-Taiba.

Ajmal Amir Kasab, 21, told investigators his recruiters promised to pay his family from an impoverished village Pakistan's Punjab region $1,250 when he became a martyr.

Kasab said he and the other gunmen were "hand-picked" for the mission and trained for more than a year by Lashkar-e-Taiba, based in Kashmir, according to two senior officials involved in the investigation. They spoke on condition of anonymity because they were not authorized to talk to media about the investigation.