A powerful blast took place near the boundary wall of a private school in Bangaon village of Gonda district, police said on Monday.
The blast left a hole in the wall. No injuries were reported.
"Shamsher Ahmed, the founder of Bright Future School in Gonda district, informed us that a bomb had exploded near the boundary of the institution at 3 am on July 21," said Assistant Superintendent of Police (ASP) Mahendra Kumar.
Kumar said that a team of police rushed to the spot and found a detonator, a gelatin rod, 400-metre wire, battery box and a bag.
A case has been registered under Section 436 (mischief by fire or explosive substance) of the Indian Penal Code (IPC) and other relevant Sections of the Explosives Act.
"The school is in a remote area. A team has been constituted for further investigation," said Kumar.