YANGON, Myanmar -- A gunman killed a legal adviser for Myanmar’s ruling National League for Democracy on Sunday, shooting the lawyer in the head at close range as he walked out of the Yangon airport, the government said.

The gunman was arrested after he killed Ko Ni, a prominent member of Myanmar’s Muslim minority, and wounded a taxi driver who tried to stop him from fleeing, the Ministry of Information said in a video posted on state-run MRTV.

Ko Ni was the Supreme Court advocate for the NLD and a longstanding legal adviser to the country’s leader Aung San Suu Kyi. He had just arrived from a trip overseas.

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A friend of Ko Ni who witnessed the shooting said the suspected assassin also shot a taxi driver who tried to stop him from fleeing.

“As I stopped my car by the airport, that’s where I saw Ko Ni’s body lying on the walkway outside of the airport and I couldn’t believe that just happened,” said Thet Paing Soe, a friend and an NLD supporter. “Then as the shooter tried to run away, the police arrested him.”

Thet Paing Soe said a taxi driver known as Nay Win stopped the fleeing assassin but was shot. The ministry’s news statement said the driver was wounded.

The Ministry of Information identified the suspect as Kyi Linn from Mandalay. The motive was not known.

Kyee Myint, a former chairman of the Myanmar Lawyer Network who has a close relationship with Ko Ni, also confirmed his death.

“It is a big loss for us that Ko Ni, our beloved friend, has been killed. He is the face of the democracy in our country and this is a big loss for us,” Kyee Myint added.

Calls to Suu Kyi’s office were not answered, and other leaders of the NLD were not reachable Sunday evening.

Ko Ni was one of the country’s most prominent Burmese Muslims. He criticized the NLD in 2015 for not putting up Muslim candidates in the general election. Myanmar is a mainly Buddhist country and anti-Muslim sentiments have increased in recent years following deadly communal violence concentrated in the western state of Rakhine that is home to many Rohingya Muslims.

Amnesty International urged an independent investigation and said the killing of Ko Ni had the hallmarks of a political assassination.

“His death will send shock waves across the human rights community in the country and beyond, and the authorities must send a clear message that such violence will not be tolerated and will not go unpunished,” said the statement from Josef Benedict, Amnesty’s regional deputy campaigns director.

The group called Ko Ni a tireless human rights campaigner and expressed condolences to his family.

As a practicing lawyer, Ko Ni had handled more than 900 criminal cases and more than 1,400 civil cases. He established the Laurel Law Firm with two other advocates in 1995.