[Backwardsman97]

Use OnPlayerInteriorChange and use GetPlayerWeaponData to store their weapons when they enter the interior and give it back when they leave.

pawn Code:

new pW[MAX_PLAYERS][13]
new pA[MAX_PLAYERS][13];

public OnPlayerInteriorChange(playerid,newinteriorid,oldinteriorid)
{
    if(newinteriorid == 0 && oldinteriorid == //interiorwithnoweapons)
    {
        for(new w=0;w<13;w++)
        {
            GivePlayerWeapon(playerid,pW[playerid][w],pA[playerid][w]);
        }
    }
    if(newinteriorid == //interiorwithnoweapons)
    {
        for(new w=0;w<13;w++)
        {
            GetPlayerWeaponData(playerid,w,pW[playerid][w],pA[playerid][w]);
            ResetPlayerWeapons(playerid);
        }
    }
}

Try that.