Complex sentence: But on January 22,1987, The Mendiola massacre occurred killing 13 people resulting another major delay the mall's opening from September 1987 to April 1988.
Split into simpler sentences: But on January 22,1987, The Mendiola massacre occurred killing 13 people resulting another major delay to the mall's opening. The opening date was moved from September 1987 to April 1988.