PESHAWAR (AP): Gunmen opened fire on the top U.S. diplomat in northwestern Pakistan early Tuesday as she left for work in her armored vehicle, police and embassy officials said. No one was killed.

Lynne Tracy, principal officer for the consulate in the bustling city of Peshawar, was 100 yards (meters) from her house when two men with AK-47s jumped out of their dark blue Land Cruiser and sprayed her car with dozens of rounds of ammunition.

Her driver reversed the vehicle and peeled back to her home, said Arshad Khan, the local police chief and senior investigator in case.

The brazen attack came hours after the collapse of the ruling coalition that drove U.S. ally Pervez Musharraf from the presidency one week ago. The breakup was not expected to bring down the government _ rather it likely places more power into the hands of a party that says it is committed to the war on terrorism.

The government has already announced a ban on the Taliban, blamed for a wave of suicide bombings in recent days. It also rejected a militant cease-fire offer in Bajur, a rumored hiding place for Osama bin Laden, where an army offensive has reportedly killed hundreds in recent weeks. The Taliban have threatened retaliation over that operation.

Tracy, an Ohio native, took up principal officer duties in Peshawar in September 2006, according to the consulate Web site.

She left her home in an upscale and heavily guarded area of the city with a bodyguard, provided by the local anti-terror squad, just after 8 a.m., Khan said. The attack indicated the assailants were familiar with her travel patterns.

Though no one was wounded by gunfire, a rickshaw driver was hospitalized after his three-wheeled taxi was hit by the consulate vehicle during its rapid retreat to Tracy's home, he said.

The U.S. Embassy provided few details about Tuesday's attack.

``There were no injuries and minimal damage to the vehicle,'' said U.S. Embassy spokesman Lou Fintor, who declined to discuss the security involved. ``We are coordinating with Pakistani authorities in investigating the incident.''

Militant activity is rampant in parts of northwest Pakistan, though mainly in tribal regions where U.S. officials say insurgents have found safe havens from which to plan attacks on American and NATO forces across the border in Afghanistan.

Peshawar, a crowded, dusty city, has not been immune, and concerns about militant activity in and around it prompted the government to stage a paramilitary offensive in neighboring Khyber tribal region earlier this year.

It is the army offensive in nearby Bajur, however, that has most angered militants, with helicopter gunships pounding their suspected hide-outs in the rugged, mountainous terrain along the Afghan border.

The U.S. has pledged US$750 million toward a five-year drive to develop impoverished areas along the frontier _ moves it hopes will reduce extremism.

Talat Masood, a political and military analyst, said American and other diplomats seen as allies in the war on terrorism could increasingly be the targets of militant attacks, especially in the next few weeks.

``I think they have to be very careful'' he said, especially as the army intensifies its campaign in tribal regions. ``They should take a low profile, their movements should be restricted during this period.''

Masood did not think Western allies should scale back their presence, however, saying that would only embolden al-Qaida- and Taliban-linked militants and demoralize Pakistanis.

There have been a string of suicide bombings since Musharraf _ a stalwart ally in the U.S. war on terrorism _ resigned as president after nearly nine divisive years in power rather than face the humiliation of impeachment.

The Taliban claimed to be behind a twin suicide bombing at a weapons manufacturing complex near the federal capital, Islamabad, that killed 67 people _ one of the largest terrorist attacks ever in the country.

The Taliban spokesman could not immediately be reached to comment on Tuesday's attack.

Pakistan, where anti-American sentiment runs deep, is considered a hardship posting for U.S. diplomats, with many coming for one-year stints without family.

However, while there are occasional attacks on Western targets, directly targeting U.S. officials is still relatively unusual. Top diplomats in particular tend to have high security and are often restricted in what places they are allowed to visit.

In 2006, a suicide attacker blew himself up outside the Karachi consulate, killing a U.S. diplomat, and in 2002 five people, including two Americans, died when a militant hurled grenades into a Protestant church in Islamabad.

This year, a bombing at a restaurant frequented by Westerners in the capital killed a Turkish aid worker and wounded at least 12 others, including four FBI personnel. A suicide bombing outside the Danish embassy killed at least six people.

Meanwhile Tuesday, in Pakistan's southwest Baluchistan province, a bomb rigged to a motorcycle parked near the stage of a political rally in the town of Jaaferabad wounded at least 20 people, some critically, police official Nazir Ahmad said.

The attacks come as the country's ruling coalition has crumbled.

Just a week before, the two main parties united to drive Musharraf from the presidency, but their partnership collapsed Monday over disputes about his successor and how to restore judges he had ousted.

The main ruling Pakistan People's Party is expected to cobble together a new coalition now that its key junior partner has quit, avoiding the need for another general election.

The People's Party, long led by slain ex-Prime Minister Benazir Bhutto, is now headed by Asif Ali Zardari, who has said he would run for president and is expected to win easily.

His nomination for the Sept. 6 election by lawmakers was submitted along with those of around 30 others on Tuesday, Election Commission Secretary Kanwar Dilshad said.

Ex-Prime Minister Nawaz Sharif's party, which broke from the coalition, has nominated retired judge Saeeduz Zaman Siddiqui.