Islamabad, Pakistan (CNN) -- The governor of Pakistan's Punjab province was assassinated by his own security guard Tuesday, according to Interior Minister Rehman Malik, apparently because he spoke out against the country's controversial blasphemy law.

The security guard was arrested, Malik said. The shooting occurred at Islamabad's Kohsar Market, which is frequented by foreigners.

The guard, Malik Mumtaz Hussain Qadri, confessed to assassinating Taseer because "he did blasphemy of the Prophet Mohammed," said Naeem Iqbal, spokesman for Islamabad police. Qadri told police Taseer had described the blasphemy law as "the black laws."

The blasphemy law makes it a crime punishable by death to insult Islam, the Quran or the Prophet Mohammed.

After the shooting, Qadri immediately surrendered to authorities, the Associated Press of Pakistan reported, citing Malik.

Taseer was leaving the market when he was shot. The APP said he had had lunch with a friend at a cafe in the market. Earlier, Iqbal had said Taseer had gone into the market to make some purchases. He was taken to a hospital following the shooting, but died, apparently from blood loss, officials said.

However, Dr. Sharif Astori, spokesman for Poly Clinic Hospital, told CNN Taseer was "already dead when he was brought into the hospital."

Astori said doctors accounted for 26 bullets in his body. Most of the fatal wounds were to his chest, face, neck and legs, he said. Some of the bullets passed completely through his body.

Taseer knew he was targeted by some because of his stance on the blasphemy law, P.J. Mir, a Pakistani journalist and friend of Taseer's, told CNN. Mir said Taseer told him when the two ate dinner together last week that he had already told his wife to consider herself a widow.

Taseer "really felt for the people, felt for the people of all religions" and was not afraid to stand up for the downtrodden, Mir said. "Today we've lost a very good man."

He said Tuesday was a tragic day for Pakistan.

A spotlight was put on Pakistan's controversial blasphemy law in November when a Christian woman, Asia Bibi of Punjab province, was sentenced to death for blasphemy. A court found the 45-year-old woman guilty of defiling the name of the Prophet Mohammed during a 2009 argument with fellow Muslim field workers.

An investigation by a Pakistani government ministry found the charges against Bibi stemmed from "religious and personal enmity" and recommended her release. The government also said it would review the law.

In remarks to CNN in November, Taseer said Pakistan's President, Asif Ali Zardari, would pardon Bibi if the courts did not.

"He's a liberal, modern-minded president, and he's not going to see a poor woman like this targeted and executed ... it's just not going to happen," he said.

"The blasphemy law is not a God-made law. It's a man-made law," he said. "... It's a law that gives an excuse to extremists and reactionaries to target weak people and minorities."

No "big, rich, powerful man" runs afoul of the law, he noted. "It's only the poor people who they want to, you know, either grab their property or threaten them or get into local disputes. So the law is actually an unfortunate leftover from a military regime. It has to go in due course or be amended, and I think the pressure is on us, is on the parliamentarians now," he said.

"People have spoken up, I'm very happy to say," he added. "I took the initiative and I think from all sides ... people are coming out and openly condemning the blasphemy law. I think that's encouraging."

Taseer said he would like to see the law "changed in such a way that it just basically says, if you insult any prophet, no matter who he is, that's a criminal offense, but certainly not punishable by death."

Reaction to the assassination from officials in Pakistan and beyond was swift. Prime Minister Syed Yusuf Raza Gilani said in a statement he "strongly condemned" the incident. The Pakistan People's Party, the nation's ruling party, said it would observe two weeks of mourning over Taseer's death, according to GEO TV.

"I am shocked to hear of the assassination of Salman Taseer," British Foreign Secretary William Hague said in a statement. "His death will be a loss to the leadership of Pakistan."

In the wake of Taseer's death, Pakistan's minority minister pledged to continue pushing for amendments in the law.

"I will continue," Shahbaz Bhatti told CNN. "I will campaign for this... these fanatics cannot stop me from moving any further steps against the misuse of (the) blasphemy law."

Asked if he was in fear of his own life, Bhatti said he was not, but "I am getting threats. I was told by the religious extremists that if you will make any amendments in this law, you will be killed. But I am ready to sacrifice my life for the principled stand I have taken because the people of Pakistan are being victimized under the pretense of blasphemy law."

The English-educated Taseer created "a host of highly successful businesses," according to his official website, and is "the pioneer of cable television in Pakistan." He introduced the first English news channel in Pakistan, Business Plus.

His website describes Taseer as an activist who stood up to Pakistan's previous military leadership, calling it a "brutal and medievalistic dictatorship." He was arrested a total of 16 times, according to the website, placed on house arrest several times and spent time in "jails around the country."

He married twice and had six children, according to his website, which also contained a quote from him: "You live life once, you live it by your principles and you live it courageously -- that's what it's about." He lived in Lahore, Pakistan.

Taseer's official Facebook page lists his favorite books as Niccolo Machiavelli's "The Prince" and biographies "of everyone -- from Napoleon to Richard Branson to Hugh Hefner."

He had been governor of Punjab province since May 2008.

CNN's Chris Lawrence and Josh Levs and journalist Nasir Habib contributed to this report.