What inspired protesters to demonstrate at tiananmen sqaure

On April 15, 1989, Hu Yaobang - a political leader in China who supported the democratic reform died. Thousands of students went to Tiananmen square, and occupied it. More than 1.2 million of people take the part in the protest. Some students starter hunger strikes, some simply stayed at one spot thus causing civil disobedience. After few days of protesting, soldiers open fire on the crowd, killing up to thousands of people and arresting about 10 thousand other.