They said nobody was injured in the blast.
SPS Nellore district Superintendent of Police Vishal Gunni said the low-intensity bomb exploded at 4 pm on the rear side of the court premises, which is rarely visited by people.
The court is around 280 km from here.
"The explosion left a dark spot. It was a low-intensity blast and we gathered some clues to determine the type of explosive material used. No one was injured," Gunni told PTI over phone.
Police sounded an alert following the incident and launched a hunt for the suspects.
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