rosrun can't find gazebo executable
I just installed gazebo. Everything went fine but when I went to test it using the commands
roscore &
rosrun gazebo_ros gazebo
I got the error
[rosrun] Couldn't find executable named gazebo below
/opt/ros/hydro/share/gazebo_ros
It's strange because tab completion still works and everything appears to be in the correct directories.
Thank you for any help