Police remain on guard at the Midtown building where four people were killed Monday, making sure it is kept secure while detectives dig into the case.

A fifth person who was shot survived. Police credit panic rooms inside the building with helping save lives.

Police in Las Vegas say a licensed gun dealer remembered seeing Tamura at a gun show in June.

He says Tamura tried to buy a special trigger for an M-4 rifle, then returned it the next day because he needed money for ammo and came back with cash to buy it again.

Detectives in Nevada are also searching his home, talking to the gun dealer and trying to figure out what led to the shooting.

News 12 spoke with a worker who said walking by the area brings back all the fear and emotions felt on Monday.