Around 30 people, including law enforcers, were injured in the clash at Thakurparha village in Khaleya union on Friday afternoon, police and doctors said.
Rangpur Medical College Hospital Assistant Director Shafiqul Islam said 11 people hit by rubber bullets and shotgun shells were brought to the government-run facility.
Seven of them were in a critical condition after being hit by bullets in the head and stomach, Shafiqul said.
The others in 'critical' condition are 'Mahbubul', 25, 'Jamil', 26, 'Alim', 32, 'Jahangir', 28, 'Amin', 26, and 'Ripon', 28.
Rafiqul Islam Master, a member of the village's Paglapeer Jam-e-Masjid managing committee, told bdnews24.com that a young man uploaded a 'blasphemous' photo some days ago.
The locals took out a procession against the post on Tuesday, demanding the youth's arrest, said Rafiqul, one of the key organisers of the protests.
As their demand was not met, they took out another procession on Friday afternoon and attacked the Hindu homes, Rafiqul said.
Gangacharha Police Station OC Zinnat Hossain said the attackers torched the houses of the nine families in a 'planned manner'.
He also said a local grocer on Oct 29 started a case against the Hindu man who allegedly posted a blasphemous photo on Facebook.
Police went to the Hindu man's house but could not find him, the officer said.
The victims of the arson attacks said hundreds of attackers burnt their houses down.
"We couldn't save anything," said Jiten Bala, an elderly woman.