Tributes are being paid to the victims of monday nights attack. The suspect, salman abedi, a 22 year old born in manchester to libyan parents had been known to Security Services. It is said it is unlikely he was acting alone. The Terror Threat alert has been raised to critical, its highest level. More rate of taken place across the city today as Police Continue their investigation. So far, four people have been arrested, one is the suspects older brother. The bbc understands the bomber is thought to have detonated a device built by someone else. The Terror Threat alert indicates further attacks may be imminent. Hundreds of troops have been deployed to protect key sites across the country, including Downing Street. An Off Duty Female Police Officer was among the 22 killed in the attack. Husband is critically ill and their two children were also injured. We will have all the latest elements in manchester and reaction, but first this report. Of those killed in the attack on monday night,