The death toll could still rise, as at least 45 people were wounded and rushed to hospital. Some are in critical condition as a result of the blasts, ministry spokesman Wahid Majroh told the Afghan Tolonews.
The journalists were targeted in the second explosion, which occured minutes after the first.
"The bomber disguised himself as a journalist and detonated himself among the crowd," said police spokesman Kabul Hashmat Stanikzai.
The first bomb was detonated by an assailant on a motorcycle and left at least four dead and five injured, according to the interior ministry.
Stanikzai confirmed that journalists had been killed, but said he did not know how many. Along with Marai, it is believed one journalist from 1TV and seven from Tolonews were among the dead.
Marai joined AFP as a driver in 1996, the year the Taliban seized power, and began taking pictures on the side, covering stories including the US invasion in 2001.
In 2002 he became a full-time photo stringer, rising through the ranks to become chief photographer in the bureau.
The Islamic State group claimed responsibility for the attack, which occured near the Afghan intelligence services headquarters shortly before 8:00am local time.
The blasts come days after the Taliban kicked off their annual spring offensive, a rejection of the Afghan government's offer of peace talks.
During the announcement, the Taliban vowed to target US forces and "their intelligence agents" as well as their "internal supporters".
The blasts follow a string of bloody attacks across the country including a bombing that targeted a voter registration centre in Kabul that killed at least 57 people last week.
The Taliban said the offensive was partly a response to US President Donald Trump's new strategy for Afghanistan announced last August, which gave US forces more leeway to go after insurgents.
President Ashraf Ghani's government is under pressure on multiple fronts this year as it prepares to hold October's long-delayed elections while its security forces struggle to get the upper hand on the battlefield and prevent civilian casualties.
Officials have acknowledged that security is a major concern because the Taliban and other militant groups control or contest large swathes of the country.
Many Western and Afghan officials expect 2018 to be a particularly bloody year.
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