An officer said the scene currently involved the entire corridor including the flat.
One neighbour from the same floor of the building, who did not wish to be named, told PA: “I’ve only spoken to him for 30 minutes, I didn’t know the guy but it makes me scared. I have a son.
“I had no idea he (the suspect) could do something like this.”
Home Secretary Priti Patel has issued a statement, condemning the attack.
She said in a statement on Saturday: “This evening we saw a senseless attack on people simply enjoying a Saturday evening with family and friends.
“My heart, prayers and thoughts are with all of those affected and to the people of Reading who will be deeply shocked and concerned by this terrible incident.