For instance, read this story of Ishmael:
"But in the seventh month, Ishmael son of Nethaniah, son of Elishama, came. He had royal blood in his veins and had been one of the king's high-ranking officers. He paid a visit to Gedaliah son of Ahikam at Mizpah with ten of his men. As they were eating together, Ishmael and his ten men jumped to their feet and knocked Gedaliah down and killed him, killed the man the king of Babylon had appointed governor of the land.
Ishmael also killed all the Judeans who were with Gedaliah in Mizpah, as well as the Chaldean soldiers who were stationed there. On the second day after the murder of Gedaliah - no one yet knew of it - men arrived from Shechem, Shiloh, and Samaria, eighty of them, with their beards shaved, their clothing ripped, and gashes on their bodies. They were pilgrims carrying grain offerings and incense on their way to worship at the Temple in Jerusalem.
Ishmael son of Nethaniah went out from Mizpah to welcome them, weeping ostentatiously. When he greeted them he invited them in: "Come and meet Gedaliah son of Ahikam." But as soon as they were inside the city, Ishmael son of Nethaniah and his henchmen slaughtered the pilgrims and dumped the bodies in a cistern.
Ten of the men talked their way out of the massacre. They bargained with Ishmael, "Don't kill us. We have a hidden store of wheat, barley, olive oil, and honey out in the fields." So he held back and didn't kill them with their fellow pilgrims.
Ishmael's reason for dumping the bodies into a cistern was to cover up the earlier murder of Gedaliah. The cistern had been built by king Asa as a defense against Baasha king of Israel. This was the cistern that Ishmael son of Nethaniah filled with the slaughtered men.
Ishmael then took everyone else in Mizpah, including the king's daughters entrusted to the care of Gedaliah son of Ahikam by Nebuzaradan the captain of the bodyguard, as prisoners. Rounding up the prisoners, Ishmael son of Nethaniah proceeded to take them over into the country of Ammon."
-- Jeremiah 41:1-10