Gunmen killed Pakistan's main government prosecutor on the Benazir Bhutto murder case in Islamabad before escaping on a motorbike, police said.

State prosecutor Chaudhry Zulfiqar Ali was shot in the head, shoulder and chest in the attack on Friday as he was driving to a hearing in the murder case of the former prime minister, who was assassinated in 2007.

Bullets hit the lawyer at least 13 times, and his car was left pockmarked and with a shattered windshield, police officer Arshad Ali said.

The attack happened in broad daylight in a busy street in a middle-class neighbourhood of the Pakistani capital.

His bodyguard was also wounded and a woman was killed when Zulfiqar lost control of his vehicle, police said.

Bhutto's husband, President Asif Ali Zardari, strongly condemned the prosecutor's slaying and called for a thorough investigation.

A motive for the killing was unclear, but his involvement in two particularly high-profile cases will likely be scrutinised closely.

Security requested

Zulfiqar was also leading the investigation into a case related to the 2008 terrorist attack on the Indian city of Mumbai that killed 166 people.

The attack was blamed on the Pakistan-based group Lashkar-e-Taiba. Pakistan has put seven men on trial on charges they assisted in the Mumbai siege, but the trial has made little progress.

Zulfiqar was scheduled to appear in an anti-terrorism court in the neighbouring city of Rawalpindi on Friday, according to Al Jazeera's Kamal Hyder in Islamabad.

Our correspondent said Zulfiqar had recently requested additional security from the ministry of interior “because of the high-profile case that he was investigating.”

“However, none of that was given and only one guard was riding with him,” Hyder said.

Musharraf house arrest

On Tuesday, ex-military ruler Pervez Musharraf was placed under a two-week house arrest over charges that he conspired to murder the former prime minister, who was at the time campaigning for election.

Musharraf denies being involved in Bhutto's killing, and his government blamed it on Pakistani Taliban chief Baitullah Mehsud, who denied any involvement and was killed in a US drone attack in 2009.

Bhutto's son, Bilawal Bhutto Zardari, chairman of the outgoing main ruling Pakistan People's Party, has accused Musharraf of her murder.

In 2010, a UN report said Bhutto's death could have been prevented and accused Musharraf's government of failing to give her adequate protection.

Zulfiqar's colleagues described him as a highly competent prosecutor.

"He had a vast experience of handling complicated and high-profile cases and because of his competence he was assigned the Benazir Bhutto case and some other cases," said Ashraf Gujar.