Story highlights The doctor is a Pakistan native but has Canadian and U.S. citizenship

Pictures of his bloodied body have gone viral on social media

The motive of the killing is unclear

An American doctor was killed when gunmen on motorcycles riddled his body with bullets while he was visiting a graveyard in Pakistan, authorities said.

Dr. Mehdi Ali Qamar was a cardiologist and resident of Fairfield, Ohio.

He arrived in Rabwah town in Punjab three days ago to provide free medical care to heart patients.

The doctor was visiting a local graveyard at sunrise Monday when two waiting gunmen shot him and took off, according to Azhar Abbas, a local police official.

The motive of the killing is unclear.

Qamar died instantly, and pictures of his bloodied body have gone viral on social media.

The doctor, who's also a poet and an artist, was visiting the graveyard with his wife and 3-year-old son when the shooting took place.

Qamar is a Pakistan native, but has Canadian and U.S. citizenship.

He is the second member of the Ahmadiyya Muslim Community killed in Pakistan this year.

Ahmadiyya Muslim Community members have been constantly persecuted in Pakistan since 1974, when a constitutional amendment declared them non-Muslim. A decade later, President Muhammad Zia ul Haq's military regime amended Pakistan's penal code. This barred Ahmadis from identifying as Muslims and led to a hate campaign against their community.

Khalil Ahmad, 61, was arrested on blasphemy charges and fatally shot this month while in police custody in the Punjab town of Sharqpur. He was shot dead by a man who came in to serve food to prison inmates, according to Saleem Uddin, a spokesman for the Ahmadi community.

Qamar's family will travel to Canada to bury his body in Toronto. "He had no enemies," the spokesman said. "He was a gentle man who enjoyed playing cricket."

"Our community will continue to provide services to this country, It is this ongoing process of hate and discrimination that needs to be stopped in Pakistan."