A total of 19 people were arrested and seven police officers hurt during disturbances in Derry last night, police said today.
A petrol bomb is hurled at police at Butcher Street in Derry
More than 50 petrol bombs were thrown during a series of riots across the city following the Orange parade in the city.
Superintendent Johnny McCarroll said the PSNI was determined to catch troublemakers and a dedicated team of officers had been set up to investigate the disorder and study CCTV footage to identify those involved.
"Where there is evidence of offences, arrests and prosecutions will follow in the coming days and weeks," he said.
"The disorder involved a small minority of people who brought what had been a very successful day in the city to a close with mindless violence," he added.
The Orange parade in Derry had been one of the quietest held in the city in recent years. Just over 3,000 Orangemen paraded through the centre for the first time in 13 years, after a deal was reached with nationalists.