[Mean]

You didn't put it to go back. Make a timer to go back after few seconds.

pawn Код:

SetTimer( "GateClose", 3500, 0 ); // Closes the gates after 3.5 seconds.

Put that in your command. ^^
Later in the script

pawn Код:

forward GateClose( ); 
public GateClose( )
{
    // MoveObject code here, to close the gates. 
    return 1;
}