The family of the soldier hacked to death in Woolwich has paid tribute to "a loving son, husband, father, brother and uncle" who always wanted to be in the Army and "live life and enjoy himself".
Drummer Lee Rigby, 25, was killed by two assailants on the streets of south east London on Wednesday.
A total of four people, including two men shot by police at the scene, have now been arrested in connection with the brutal attack.
Scotland Yard said a man and a woman, both 29, were held on Thursday on suspicion of conspiracy to murder and are being questioned at a police station in south London. The two men who were shot, aged 22 and 28, have been arrested on suspicion of murder and remain in hospital in a stable condition with non life-threatening injuries.
Drummer Rigby's family issued the following tribute: "Lee was lovely. He would do anything for anybody, he always looked after his sisters and always protected them. He took a 'big brother' role with everyone.
"All he wanted to do from when he was a little boy, was be in the Army. He wanted to live life and enjoy himself. His family meant everything to him. He was a loving son, husband, father, brother, and uncle, and a friend to many. We ask that our privacy be respected at this difficult time."
Six residential addresses were being searched as part of the investigation, three in south London, one in east London, one in north London and one in Lincolnshire. Officers have recovered a number of items from the murder scene and continue to appeal for witnesses to get in touch, and send in footage and photographs of what happened.
On Thursday evening US president Barack Obama issued a statement to say: "I condemn in the strongest terms the appalling attack against a British service member in Woolwich on May 22.
"The United States stands resolute with the United Kingdom, our ally and friend, against violent extremism and terror. There can be absolutely no justification for such acts, and our thoughts and prayers are with the family of the victim, the police and security services responding to this horrific act and the communities they serve, and the British people."
Meanwhile, hundreds of bunches of flowers were tied to the railings of the barracks at the corner of John Wilson Street and Artillery Place, or placed on the wall. Among the floral tributes were small wooden crosses bearing poppies, with "In Remembrance" written underneath. Cards and messages read: "Goodnight and God bless young man", "Such a senseless act" and "A young man taken so tragically".