Emergency services have been searching the River Ribble for a teenager who went missing at the weekend, say police.
Police say that a specialist water rescue unit from Lancashire Fire and Rescue have been trying to locate missing Michael Brookes who was last seen in the early hours of Sunday morning.
The search initially focused on the area around the park but was widened along the river to the Preston Docks area.
Bowland Mountain Rescue Team, search dogs, a drone and boats from Penwortham have all been called out to assist in the search which is now in its fourth day.
A spokesman for the police confirmed that the 19-year-old has not been found.
Missing Michael was reported to have been in the company of a friend on Avenham Park when he left the park alone.
The 19-year-old has not been seen since.
A spokesman for the police said in a tweet: "Today sees for the fourth day of searching for missing person Michael Brookes.
"Local officers are being assisted by @NPASHawarden, @MCA_Media, @SouthportRescue, @EnvAgencyNW and NW Police Underwater Search & Marine Unit. "
Michael is described as white, around 5ft 7ins, of slim build with short dark hair. He speaks with a Liverpudlian accent and was last seen wearing black skinny jeans and a black hooded top with a camouflage pattern at the bottom.
Anyone with information should contact police on 101.