The body of a newborn baby girl has been found at a waste management site.
West Yorkshire Police said the discovery was made by staff at a firm in Valley Road, Bradford, at around 2.30am today.
A force spokesman said: "Emergency services attended and it was confirmed the baby girl was already deceased.
"An investigation is under way to identify the child and the circumstances surrounding the discovery of her body.
"We have serious concerns for the health and welfare of the mother and ask her or anyone who may have information to contact the police as soon as possible."
He said a post-mortem examination will be conducted later today to determine the cause of baby's death.
At a news conference in Leeds, Detective Superintendent Sukhbir Singh said his priority was tracking down the mother of the baby.
"I am genuinely concerned for the safety and welfare of the mother and my overriding priority is for her safety," he said.
It is believed the baby was born recently.
Parts of the site at Association Waste Management remained sealed off today.
Police officers were on guard outside the premises, which is between Bradford and Shipley.