Several police officers have been injured during a search operation following a murder in Belfast.
There were further disturbances on Tuesday
A number of homes have been searched by police investigating the fatal stabbing of a man outside a bar in the city.
Residents said police went to premises around Madrid Street and Perry Court in the Short Strand area of east Belfast at about 0730 GMT on Tuesday.
A team of forensic scientists examined the rear of a property and a white car was taken away for further inquiries.
There were further disturbances on Tuesday as officers were subjected to stone-throwing.
A car was set on fire close to the Markets area and several police vehicles were damaged.
A senior republican was one of four men being questioned about the murder of Robert McCartney.
One of the four was released without charge on Tuesday evening.
Mr McCartney, 33, from the Short Strand area died from stab wounds following an incident at about 2300 GMT on Sunday.
He was found unconscious in Cromac Street. It is understood police are treating the incident as a pub fight.
Officers were attacked with bricks, bottles and stones during searches linked to the investigation on Monday night.
The attacks happened as police attempted to search properties in the Markets area.
At one stage officers dressed in riot gear pushed the crowd back.
Pensioners living in Upper Stanfield Street were caught up in the middle of the violence, and some said it was the worst street fighting they had seen for some time.
A search linked to the murder took place in Short Strand on Tuesday
Former mayor Alex Maskey of Sinn Fein said "heavy handed" police tactics had caused the trouble.
He said police were in the area from early morning but there was no attack on them until they "started to kick down doors of known republican homes".
"The death of that man was an excuse for the PSNI to come into that area, reminiscent of what the RUC would have done years ago," he said.
"It is very regrettable that what appears to have been a very tragic incident at a bar has been turned into a serious political situation."
The police said the attacks on them were regrettable and have appealed for anyone with information to contact them.
Meanwhile, Magennis's Bar in May Street has been cordoned off while forensic scientists search the area where the stabbing took place.