Afghan officials say at least 11 civilians have been killed by a roadside bomb in the western province of Farah, while another six died when unidentified gunmen stormed a government building in the eastern city of Jalalabad.
Farah provincial governor spokesman Naser Mehdi told RFE/RL that about 40 people were also wounded when the explosion hit a bus that was traveling through Bala Baluk district on the morning of July 31.
The bus was on its way from western Herat Province toward the capital, Kabul.
No group immediately claimed responsibility for the bombing, but provincial police spokesman Muhibullah Muhib put the blame on the Taliban, which has a strong presence in Farah Province.
"It was a bomb planted by the Taliban to hit security forces, but unfortunately it got a passenger bus," Muhib said.
Women and children were among those killed and wounded in the blast, officials said.
The death toll was expected to rise as some of the passengers of the bus were in critical condition.
Civilians have borne the brunt of the 17-year conflict in Afghanistan and improvised explosive devices are one of the main causes of casualties.
A total of 10,453 civilian casualties -- 3,438 people killed and 7,015 injured -- were recorded by the UN Assistance Mission in Afghanistan last year.
In Jalalabad, a suicide bomber blew himself up in front of the entrance of the compound of the refugees and repatriations department, clearing the way for gunmen to storm the building, provincial council member Zabit Mir Ahmad said.
Attaullah Khogyani, spokesman for Nangarhar Province's governor, said at least six people died in the attack and at least 14 more were wounded.
There was no immediate claim of responsibility for that attack. The Taliban denied involvement in a WhatsApp message sent to journalists.
The assault comes three days after militants raided a midwife training center in Jalalabad, killing at least three people and wounding several others. The Islamic State (IS) extremist group claimed responsibility.
Jalalabad has been the scene of multiple attacks in recent months that have killed dozens, as the Western-backed government in Kabul continued to struggle to fend off the Taliban and other militant groups since the withdrawal of most NATO troops from Afghanistan in 2014.