He is suspected to be the ringleader of Easter Sunday attackers.
Police Spokesperson Ruwan Gunasekara told Xinhua that the clashes had erupted due to a personal dispute between two individuals which soon escalated between two groups clashing on streets.
The authorities have blamed the Easter Sunday attacks, which also killed 42 foreign nationals, on two little-known local Islamist groups, the National Tawheed Jama'ath (NTJ) and Jamathei Millathu Ibrahim (JMI).
"Until we are certain about the security situation outside we will not send the child to school", Dissanayake said.
On being asked why Sri Lanka had not acted on the intelligence inputs shared by India on the attacks, the army chief said, "there was a gap in the government that everybody could see today".
Tensions gripped Negombo on Sunday as authorities prepared to reopen public schools after an extended Easter vacation following the suicide attacks.
Catholic services are being canceled for a second weekend in Sri Lanka's capital after the government warned of more possible attacks by the same Islamic State-linked group that carried out Easter suicide bombings.
The training camp was found in a residential area for the poor located on the outskirts of the hometown of Zahran Hashim, who is believed to be one of the main plotters of the Easter Sunday terror attacks.
He said at least one police officer will be assigned to each school for this objective. The US Federal Bureau of Investigation and Interpol, as well as other undisclosed foreign agencies, are helping Sri Lanka with the probe.
Security remained tight across the country as state schools resumed classes on Monday, but many anxious parents kept their children at home.
It was the first reported outbreak of violence since the bombings on churches and luxury hotels that left 257 dead. "They must only serve to strengthen our resolve to work in partnership with countries around the world to counter the global terrorist threat", the minister said following his trip.
Sri Lanka has imposed a state of emergency since the attacks and given sweeping powers to soldiers and police to arrest and detain suspects for long periods. The cases we faced at that time [were] more hard, and [involved] more terror than what we are facing today.