(CBS) — As police and prosecutors determine what charges to place against the two would-be thieves who took two adults and six children hostage in south suburban Harvey, Cook County Sheriff Tom Dart says his chief negotiator told him that in 150 such cases, he had never seen one like it.

An exhausted Dart told reporters that the negotiations were a “roller-coaster ride” that early on showed signs of cooperation. At one point, he said, the gunmen traded a child for cigarettes. Dart said police turned down another request, for a car in which they could make a getaway. But as time wore on, they made increasingly violent threats – including a series of threats to execute all of those they held, which eventually prompted the decision by SWAT teams to go in.

“They were not coming peacefully,” Dart said. This wasn’t something where they would come easily or peacefully. It wasn’t a part of their plan.”

He said the children took it the worst, and although they were physically unharmed, they were “terrified” by what they had seen and survived.

Dart says there is ample evidence that the gunmen fired on the SWAT team that ended the standoff by storming the house, on the 14700 block of Seeley Avenue. At the beginning of the standoff, they fired on arriving police officers, wounding two.

Dart said that both gunmen were on parole. One has served six prison sentences, the other five.

Much of the information released during the standoff came from a Harvey city spokesman, who said he obtained his information directly from Harvey’s police chief. Dart said negotiations were not helped by the information Harvey officials released. He said some was erroneous and some was sensitive information, and said Harvey police were peripheral to the effort.

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