shutting oneself in; holing up (in a room)
Refers to isolating oneself in a room or enclosed space, often for a long period. Common in contexts like hikikomori or refusing to come out.
His holing up in his room is continuing.
barricading oneself; holing up (in a building)
Used when someone barricades themselves inside a building or fort, often in a standoff or siege situation. Frequently appears in crime news.
The criminal barricaded himself in the bank and took hostages.