BuddyPress.org

I am sending to notification to multiple users with following code

 bp_notifications_add_notification( array(
	        'user_id'           => 3,1,
	        'item_id'           =>$postid,
	        'component_name'    => 'Event2',
	        'component_action'  => 'custom_action',
	        'date_notified'     => bp_core_current_time(),
	        'is_new'            => 1,
	    ) );

but notification is only send to first user id 3. How I will send the notification to multiple user id. Please help