Petrol bombs have been thrown at police officers in Londonderry on the sixth consecutive night of violence in the city.
The city’s walls close to the Bogside have been closed after petrol bombs were thrown from that area.
A fire has been started at the bottom of the Lecky Road flyover.
Police have asked motorists to avoid the road because of an “ongoing disturbance”.
The PSNI also tweeted that a “large crowd” was gathering in the area and that “there are young children involved”.
BBC News NI’s Kevin Sharkey said that a large police presence, including officers in riot gear, had gathered around the city’s walls, while a big crowd had also gathered in the Bogside.
SDLP leader Colum Eastwood said the violence was only succeeding in “terrifying people in their own homes”.
“These people who are supposedly republicans, who are supposedly trying to get a United Ireland are destroying their area,” he said.
“Now, I don’t know how many times we have to learn this lesson that this does not work.
“It’s not only morally reprehensible, it’s strategically stupid.”
A Twelfth of July parade passed off peacefully in Londonderry earlier on Thursday, although police in riot gear separated a group of nationalists from the return parade as it made its way through the Diamond in the city centre.
On Tuesday, police said dissident republicans were responsible for automatic gunfire directed at officers.
Then, on Thursday, the PSNI said two viable devices were thrown at officers on Derry’s walls.
PSNI Supt Gordon McCalmont described it as a “reckless act” that showed “a blatant disregard for life”.