When the class was over, the students ran out, screamed and shouted.

• A. 
  As long as the class finished, the students ran out, screamed and shouted.
• B. 
  No sooner was the class over, the students ran out, screamed and shouted.
• C. 
  As soon as the class had finished, the students ran out, screamed and shouted.
• D. 
  If the class was over, the students would run out, scream and shout.