This is pure Brad mental, declares Glasgow

THE centre of Glasgow was rocked by explosions as filming for the Hollywood horror World War Z got into its stride.

Hundreds of excited onlookers gathered behind safety barriers in the city's George Square to catch a glimpse of the film's star, Brad Pitt, who was in action throughout the day yesterday.

The morning's shooting was low-key, with Pitt spending much of it being filmed sitting in a silver Volvo car on Cochrane Street - which has been transformed to look like downtown Philadelphia and packed with American cars and vans - before retreating to his white trailer on John Street for much of the afternoon.

This caused a crowd to gather at the top of street, as onlookers armed with cameras hoped to catch him as he emerged for another scene. Instead they had to settle for the actor's body double walking back and forth from the set.

During his time in Scotland, the star is staying with his partner, actress Angelina Jolie, and their children at Carnell House, a secluded country retreat near Hurlford in Ayrshire.

Jolie and their six children will have the run of the 16th- century residence.

• In pictures: Filming gets under way in Glasgow for Brad Pitt horror movie

The B-listed luxury country house has 10 en-suite bedrooms and sits in a secluded 10-acre garden and is renowned for its game shooting.

By early afternoon, the production stepped up a gear and the spectators were given a real taste of Hollywood action excitement.

A shout of "action" prompted two US motorcycle police officers to come tearing up the busy street, sirens screaming, towards George Square, forcing the on-set traffic to swerve out of the way.

From behind them a loud explosion detonated out of sight, causing the dozens of extras walking along the street to turn and stampede from the blast.

The explosion scene was the repeatedly played out, sometimes without the police officers, sometimes with only a small section of the crowd, but the spectators lapped up the action, with one woman enthusiastically commenting to her friends: "This is mental!"

The film is based on Max Brooks' 2006 novel World War Z: An Oral History Of The Zombie War, part of which is set in Philadelphia in the aftermath of a zombie holocaust. It is due to be released next year.

Even when shooting stopped, people remained in the square, wandering around and examining its new appearance - hot dog and pretzel stalls, the rebranding of the City Chambers as the five star "Liberty Grand Luxury Hotel" and the clusters of road signs, fire hydrants and newspaper vending machines waiting to be put in place.There were few glimpses of Pitt, the majority of his scenes were filmed behind black screens, but the crowds seemed delighted to be part of the whole circus.

Gavin Valentine, 29, from London, said: "I'm up visiting my cousin, but when I heard this was happening I had to come down and see. So far, I haven't seen Brad Pitt but I'm amazed at the way they've transformed George Square, it looks so American."

Others, however, were appreciative of what the shoot means for the city.

Tracy Quinn, 38, of Glasgow said: "I came down because I saw the photos my daughter took of the set yesterday and it seemed such a novelty, and I know that a lot of people are here just to try and snatch a look at Brad Pitt.

"But this is a really big deal for the city and it's meant to be bringing in something like 2 million for the businesses. It's great to see the place buzzing like this."

Alana McKellar, 31, also from Glasgow, added: "I heard that there a few people who came down on Monday dressed up as zombies, hoping that they might get taken on as extras. I'm not sure if it worked but you can't blame them for trying."

At the end of each day? Pitt has been shuttled back to his family in a blue Jaguar.