Tolo TV network, one of the Afghan broadcasters apparently targeted, put the death toll at seven civilians.
Earlier, Afghan Deputy Interior Minister Mohammad Ayoub Salangi said six civilians, including four women, had died, and at least 24 others were wounded in the Kabul blast.
The bomber targeted a bus carrying staff members from Tolo TV and video production company Kaboora Productions, Afghan Chief Executive Abdullah Abdullah said.
Afghanistan's parliament building and the Russian Embassy are on the road where the blast occurred. It was not clear if the attack wounded any Afghan public officials or foreign diplomats.
claim responsibility for the bombing, wrote Zabihullah Mujahid, a spokesman for the Taliban's self-declared Islamic Emirate of Afghanistan, via email. He accused Tolo TV of being part of the West's intelligence network.
The Taliban's purported involvement in Wednesday's attack isn't a major surprise, given its longstanding and violent opposition to free expression and other rights. The group issued a threat against the independent Tolo TV network
The White House condemned the attack and one in Pakistan
at a university.
The attacks "underscore the ongoing threat that terrorists pose to the region and to the peaceful and prosperous future we seek to build together," National Security Council spokesman Ned Price said
. "We offer our deepest condolences to the victims of the attacks and to their families."
The U.S. Embassy in Kabul said a "vibrant media" is one of the successes to emerge after the United States invaded the country following the September 11, 2001, terrorist attacks
"Murdering those who work to enlighten, educate and entertain will not stop Afghans from exercising their universal human right to freedom of expression," the embassy said.
Taliban one of many violent forces in Afghanistan
The Taliban has been battling the Afghan government and its foreign allies since being ousted from power after the U.S. invasion.
Yet it is hardly the only group responsible for recent violence in Afghanistan.
Under its late leader Osama bin Laden
, al Qaeda long called the mountainous Asian nation its home, and it continues to have a presence there.
That group emerged in Iraq and Syria, where it holds swaths of territory as part of what it calls its Islamic State caliphate, but has carried out or inspired attacks in many other places around the world as well.
The relatively poor, war-torn nation of Afghanistan has been one such locale, with President Ashraf Ghani warning the U.S. Congress last March
about the "terrible threat" the group poses to his country and its neighbors.
Gen. John Campbell, the commander of U.S. forces in Afghanistan, told Congress last fall that between 1,000 and 3,000 active ISIS members
were in Afghanistan. Many of these new recruits are disaffected Taliban, a fact that may have played into Russia's recent decision to share intelligence pertinent to fighting ISIS with the Taliban, its historic foe.