Authorities responded to the New England Pentecostal Church shortly after 10 a.m., Roark said.
Roark said "more than one person" was shot, but he said he could not discuss the exact number of injuries or the extent of those injuries. He did not identify the suspect or give a motive.
Hillsborough County Attorney Michael Conlon tells CNN affiliate WMUR there are no fatalities in the shooting.
Local and state authorities, including the New Hampshire State Police and representatives from the state Attorney General's Office, are on the scene, Roark said.
Lowell General Hospital has received one patient from the incident, hospital spokesperson Angela Strunk tells CNN. There is no word on the extent of the individual's injuries, Strunk says. The hospital is not expecting any other patients from the incident.
Minister was shot and killed 2 weeks ago
A memorial service scheduled for Saturday afternoon at the church was canceled after the shooting, attendee Geraldo Pagan said.
"We just came and we found all this police, all this chaos here, and they tell us that the activity will be canceled," Pagan told news media outside the church.
The service was for Luis Garcia, 60, a minister at the New England Pentecostal Ministries for six years, who was shot and killed October 1, according to WMUR.
Pelham is a town of about 12,000 people 40 miles north of Boston. It is located between two larger cities, Nashua to the west and Salem to the east, and also borders Massachusetts to the south.
Pelham began primarily as a farming community until World War ll, when growth in population and industry took hold.