At the portion of the river between the river and Manila Bay, Companies F and I of the 21st Infantry Regiment were scouting the area when they were ambushed by about 1,000 Filipinos after crossing the bamboo pole bridge to Bacoor. Fierce fighting ensued against Filipinos armed with Remington and Mauser rifles. Two of the officers of the two companies were wounded. Later, running low on ammunition, the Americans headed to the beach for safety. They were relieved by a battalion from the Ninth Infantry led by Major Clarence R. Edwards. Major Starr signaled the gunboats for support, which responded with men and ammunition from the "Helena" and "Monadnock".