Simplify the following text for a Grade 8 native English-speaking person.
Original: The event was witnessed by Mayor Villegas , Congressman Ramon Mitra , Jr. , Atty . Primitivo de Leon , and its main sponsor in the House of Representatives , Congresman Justo Albert .
Simplified: The signing was witnessed by Atty . Primitivo de Leon , Mayor Villegas , Congressman Ramon Mitra Jr. , and its main sponsor in the House of Representatives , Congressman Albert .