The Metropolitan Police said in a statement that the men were being held on suspicion of conspiracy to commit murder and that four addresses in connection with the men were being investigated.
Police did not release their identities, CNN reports.
The Washington Times reported Thursday that British police also had arrested a man and a woman, both 29, in connection with the murder.
Drummer Rigby was walking near the Royal Artillery Barracks in the Woolwich section of London on Wednesday when he was hit by a car. Two men exited the car and held the soldier against a wall, then stabbed and decapitated him with kitchen knives and a meat cleaver, according to British media reports.
One of the two suspects arrested at the scene approached a man filming the scene and suggested that the soldier had been targeted only “because Muslims are dying daily” at the hands of British troops such as him, CNN reports.