Unable to install rmf_demos package

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I get this error below when i do colcon build with rmf_demos package:

Starting >>> rmf_task_msgs                  
Finished <<< rmf_workcell_msgs [1min 39s]   
Finished <<< building_map_msgs [1min 54s]    
Starting >>> building_map_tools
Starting >>> rmf_gazebo_plugins
Finished <<< building_map_tools [2.17s]      
Starting >>> rmf_demo_maps
Starting >>> test_maps
--- stderr: building_gazebo_plugins          
/home/ip3d/rmf_demos_ws/src/rmf/traffic_editor/building_gazebo_plugins/src/door.cpp:5:10: fatal error:     gazebo_ros/node.hpp: No such file or directory
 #include <gazebo_ros/node.hpp>
          ^~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/door.dir/src/door.cpp.o] Error 1
make[1]: *** [CMakeFiles/door.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
/home/ip3d/rmf_demos_ws/src/rmf/traffic_editor/building_gazebo_plugins/src/slotcar.cpp:5:10: fatal error:     gazebo_ros/node.hpp: No such file or directory
 #include <gazebo_ros/node.hpp>
          ^~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/slotcar.dir/src/slotcar.cpp.o] Error 1
make[1]: *** [CMakeFiles/slotcar.dir/all] Error 2
make: *** [all] Error 2
---
Failed   <<< building_gazebo_plugins    [ Exited with code 2 ]
Aborted  <<< test_maps                                 
Aborted  <<< rmf_traffic                               
Aborted  <<< rmf_gazebo_plugins                        
Aborted  <<< rmf_demo_maps                              
Aborted  <<< rmf_task_msgs                              
Aborted  <<< rmf_traffic_msgs               

Summary: 12 packages finished [2min 45s]
  1 package failed: building_gazebo_plugins
  6 packages aborted: rmf_demo_maps rmf_gazebo_plugins rmf_task_msgs rmf_traffic rmf_traffic_msgs test_maps
  3 packages had stderr output: building_gazebo_plugins rmf_gazebo_plugins rmf_traffic
  8 packages not processed

But the gazebo_ros packages is installed. and the header file node.hpp can be found in /opt/ros/eloquent/include/gazebo_ros/.

Kindly help to resolve this issue. Thanks.