Seven members of al-Qaeda-linked group held over planned attacks in Karachi, police say.
He gave no motive for the killing.
Hashimzada worked for the Afghan television channel Shamshad and a number of other Afghan, Pakistani and international news organisations.
The head of the local press club said Hashimzada had been targeted because his reporting had upset key players in the region.
“This was purely a targeted killing,” Shamim Shahid, president of the Peshawar Press Club, told the International Press Institute (IPI).
“[Hashimzada] was very critical of the Taliban, and some of his reporting was unacceptable both to Pakistani and Afghan governments and intelligence agencies,” IPI quoted Shahid as saying in a statement.
“He had too much information regarding the militants, the Taliban and the intelligence agencies.”
The death follows that of at least two Pakistani journalists killed this year in the same region, which is also the scene of frequent bomb attacks.
Call for justice
The Vienna-based IPI has branded the region one of the world’s most dangerous for journalists.
“The Pakistani government must bring to justice the perpetrators of this murder so that the killers of journalists understand that they cannot operate with impunity,” David Dadge, the IPI director, said in a statement.
Pakistan’s semi-autonomous tribal areas have been beset by violence after hundreds of Taliban and al-Qaeda fighters sought refuge there following the US-led invasion of Afghanistan in late 2001.
In its 2009 report, the Paris-based watchdog Reporters Without Borders said more journalists had been killed in Pakistan this year than any other country, with local journalists facing threats from both the Taliban and the security forces.