Chelsea's new weapon of choice...smoke bombs!

He has already begun disciplinary proceedings and owner Roman Abramovich was briefed about the shocking incident on Friday afternoon. Abramovich has backed Gourlay to take swift action and the club's chief executive has vowed to discipline players and even sack staff after the extraordinary event. A Chelsea spokesman said on Saturday: 'I can confirm an investigation is under way. It is an internal matter.' It is the latest in a string of incidents at the training ground. Last year Ashley Cole accidentally shot an intern in the leg with an air rifle, and a knife was found in the youth-team dressing room. Sportsmail understands two highly-rated reserve-team players are under investigation over the smoke bomb and will face a club disciplinary panel. If they are found guilty,  Chelsea will consider terminating their contracts. Gourlay will take statements from witnesses to the event that has horrified the coaching staff at Cobham and the club confirmed they were investigating. One source claimed the training ground has descended into 'lawlessness'. Some first-team players watched the drama unfold from their own dressing-room area and manager Andre Villas-Boas was also made aware of the incident. The grenade, which was set off in one of the reserve-team dressing rooms shortly before training at 10.30am, set off fire alarms and triggered a full evacuation procedure. Fire marshals employed by Chelsea were sent into the building, but it was more than an hour before anyone  else could go back into the dressing rooms. Chelsea's initial investigations suggest the grenade may have been brought back from a paint-balling trip and one of the players then pulled the ring inside the dressing room. Some of the more responsible reserve and youth-team players are becoming worried about their safety at one of the most expensively-assembled academy systems in world football. Last December a knife described as 'something out of a Rambo film' was discovered in the youth-team dressing room. It was later claimed to have been a workman's tool which had been inadvertently left behind. Last January, Cole was forced to apologise to an intern after the England left back brought an air rifle to training and shot him in the leg in the first-team dressing room. The latest incident is beyond Villas-Boas's remit. Instead, the Chelsea manager is attempting to unite a fractured dressing room after another controversial week. The former Porto coach claimed it is impossible to have friendships with players in the dressing room and admitted it is an 'unhappy' place. Frank Lampard revealed after last week's 3-0 win over Bolton his relationship with Villas-Boas is 'not ideal' and Fernando Torres's agent claimed the  manager will soon be sacked. Villas-Boas said: 'At the moment our relationship is full of professionalism. Friendships tend to be stronger when you leave a club. 'It was the same at Porto. A couple of them have become my friends and acquaintances, people I see when I am at home. 'We had success in our professional lives so it's normal. Frank thinks something is missing, but I don't. Frank and I are not  married to each other - it's a manager-player relationship. 'Ask any player who doesn't play every time if he has a good relationship with the manager. It's an unhappy dressing room because we are fifth. If we were first in the Premier League and 17 points ahead then any problems would be put to one side.' Villas-Boas has already admitted that he has failed to convince the players his managerial methods are suited to Chelsea. He has alienated some members of the dressing room and risked his relationship with Daniel Sturridge even further. Sturridge wants to play a central striking role but Villas-Boas has told him his future is on the wing. The manager added: 'We have three wonderful strikers already and they are entitled to the position. Daniel knew that from the beginning of the season.' Chelsea head to West Bromwich Albion clinging to the hope they can scrape into fourth place and secure Champions League football. Villas-Boas is under massive pressure to achieve it, but claims he can no longer compete with Manchester City's wealth. He said: 'City have the power now - maybe in the past we had it. We have access to the best talent and we like to promote talent, but I don't think you can compare the two squads - theirs is a lot better.' Villas-Boas also revealed  Chelsea want to sign Hulk from Porto at the end of the season. Chelsea have claimed it would be almost impossible to redevelop Stamford Bridge because of planning problems. Owner Roman Abramovich wants to move to a new site and, after talks with the local council, the club said on their website: 'A complete new build of a 60,000-seat stadium at Stamford Bridge has little chance of acceptability. It would cost over £600million and require the club to play away for at least three seasons.'