The official Marine history, of the Saipan battle, describes (scroll down 90%) the scene along the island's coast on July 8, 1944:
The enemy pocketed in the area had destroyed themselves in suicidal rushes from the high cliffs to the rocky beach below. Many were observed, along with hundreds of civilians, wading out into the sea and permitting themselves to be drowned. Others committed hara-kiri with knives, or killed themselves with grenades. Some officers, using their swords, decapitated many of their troops.
Officers also killed themselves. The Emperor’s hero of Pearl Harbor, Vice Admiral Nagumo, was among those dead.
But the killing did not stop. On July 9, the final day of the Saipan battle, Lt. Colonel Chambers watched in horror as even Japanese civilians died:
During this day [the 9th of July] as we moved along the cliffs and caves, we uncovered civilians all the time. The Jap soldiers would not surrender, and would not permit the civilians to surrender.
I saw with my own eyes women, some carrying children, come out of the caves and start toward our lines. They’d be shot down by their own people.
I watched any numbers of women carrying children come down to the cliffs that dropped to the ocean. They were very steep, very precipitous. The women would come down and throw the children into the ocean and jump in and commit suicide.
I watched one group at a distance of perhaps 100 yards, about eight or ten civilian men, women and children get into a little huddle and blow themselves up...It was a sad and terrible thing...
Interpreters were summoned, and they [Americans] pleaded by amplifier for the [Japanese] civilians to come forward in surrender. No movement followed... The people drew closer together into a compact mass.
It was still predominantly civilians, but several in uniform could be distinguished circling about in the throng and using the civilians for protection. As they huddled closer, sounds of a weird singing chant carried up to us. Suddenly a waving flag of the Rising Sun was unfurled. Movement grew more agitated; men started leaping into the sea, and the chanting gave way to startled cries, and with them the popping sound of detonating grenades.
It was the handful of soldiers, determined to prevent the surrender or escape of their kinfolk, who tossed grenades into the milling throng of men, women and children, and then dived into the sea from which escape was impossible.
The exploding grenades cut the mob into patches of dead, dying and wounded and, for the first time, we actually saw water that ran red with human blood.
Not all civilians listened to the military directives, however. Some of them chose to live, instead of die. And ... soldiers from the 27th Infantry were able to rescue an infant, covered with flies, whom they found in a cave filled with hundreds of dead bodies.