She and three men were taken to hospital with gunshot wounds after the incident at the Lighthouse Inn in Wallasey Village on the Wirral shortly after 11.50pm.

The woman was later pronounced dead, and her family are being supported by specially trained officers.

Police said a number of other people were also injured.

A cordon has been set up in the area while officers speak to witnesses and examine CCTV footage.

Detective Superintendent Dave McCaughrean, of Merseyside Police, said: "This investigation is in the very early stages, and we understand that this is a truly shocking and devastating incident that has happened just before Christmas Day in a busy venue full of young people.

"We have a number of officers at Wallasey Village who are carrying out extensive inquiries to understand exactly what has taken place and take immediate action.

"A woman has tragically lost her life at Christmas whilst several people are being treated in hospital, and our thoughts and condolences are with the victim's family.

"I would ask anyone who was in the Lighthouse in Wallasey Village last night who witnessed the incident or has mobile or CCTV footage of what happened to contact us as a matter of urgency as they may have information which is vital to our investigation.

"We believe that the gunman left the pub car park in a dark-coloured vehicle - possibly a dark-coloured Mercedes, shortly after the shooting, and we are keen to hear from anyone who saw this to contact us immediately."

Neighbour Jenny Hough, 77, said she heard the shots being fired, but believed they were fireworks instead.

"I just thought it was people celebrating midnight on Christmas Day.

"I couldn't believe it when I looked outside, I thought 'oh crikey'. It's a complete shock.

"My sister's garden had been broken into. We suspect it was people trying to get out of the pub and trying to climb over the wall and into her garden to get out."

Ms Hough added there is tight security in the area on Christmas morning.

The Lighthouse pub has called the shooting "a tragedy beyond words" in a statement, adding: "All our thoughts are with the friends and family of our customers and in particular our hearts go out to the family of our customer who has lost her life.

"We are completely shocked by this and were expecting to host a number of people for Christmas Day meals, but sadly this is no longer possible."

The MP for Wallasey, Dame Angela Eagle described the news as "heartbreaking" and urged anyone with information to contact the police.

She tweeted: "My thoughts are with the family of the woman who has died and those who are injured."

The pub is "central" to the local community, the minister at a nearby church said.

Jeffrey Hughes, minister of the United Reformed Church in Wallasey Village, said news of the fatal shooting will have come as a shock to people in the area.

He told the PA news agency: "Wallasey Village is a fairly lively area, it's a nice part of Wallasey, it's a nice part of the north end of the Wirral.

"We've got a lot of young people, families in that area. The Lighthouse is central in that community.

"It's a shock. When we first heard the news this morning that there'd been a shooting in Wallasey, Wallasey Village is the last place you would think of."

He said trying to find words of hope in "such a terrible situation" is challenging and acknowledged that the Christmas morning service would now not be "as much a celebration as it was going to be".

Anyone with information is asked to DM @MerPolCC or @CrimestoppersUK anonymously on 0800 555 111 quoting log 1044 of Saturday 24 December.