An explosion occurred in Pugoda town, about 40 km from Colombo, in Sri Lanka on Thursday, reported Reuters. The police, however, ruled out any casualties. The blast came amid severe tension in Sri Lanka following serial bomb blasts on Easter Sunday that killed at least 359 people and wounded about 500. At least 10 Indians have been killed in the attacks.

Police spokesperson Ruwan Gunasekera said they were investigating the blast that took place on a vacant land behind the magistrate’s court in Pugoda. “There was an explosion behind the court, we are investigating,” Gunasekera said.

On Wednesday, Sri Lankan President Maithripala Sirisena had asked Defence Secretary Hemasiri Fernando and Inspector General of Police Pujith Jayasundara to resign over their failure to prevent the blasts in the country despite receiving prior intelligence.

Thousands of troops were deployed overnight to help police search for suspects, AFP reported. Police have arrested or detained 75 suspects so far. The government has acknowledged that there were “major lapses” in the security arrangements.

A spice trader is in custody on suspicion that he helped his two sons, who blew themselves up in the attacks, CNN reported. Police said an Egyptian and several Pakistanis were among those detained overnight but their role is unclear, Reuters reported.

The Islamic State group has claimed responsibility for the serial bomb blasts. However, the group did not provide any evidence of its involvement.