As many as 16 bodies remain in the high school this morning, as FBI and SWAT team experts comb the sprawling building, searching lockers and school bags for bombs and booby traps. Earlier reports had put Tuesday’s death toll as high as 25, but authorities lowered the number this morning.

Law enforcement officials are also concerned with preserving evidence of the grisly scene, which around 11:30 a.m. Tuesday, changed from a normal surburban high school to a place where students were hiding under desks and begging for their lives from two juniors at the school, identified by authorities as Eric Harris, 18, and Dylan Klebold, 17.

Ten of the 23 victims who were hospitalized following the attack are now listed in serious or critical condition at area hospitals.

Police say the Harris and Klebold, clad in black trench coats, swept through the building with guns and explosives. Several students said the killers were gunning for minorities and athletes.

Student Crystal Woodman told ABCNEWS’ Good Morning America today, “They thought it was funny. They were just like, ‘Who’s next? Who’s ready to die?’ … and every time they’d shoot someone, they’d holler, like it was, like, exciting.”

The gunmen exchanged gunfire with police and were later found dead in the school library with self-inflicted gunshot wounds and bombs around their bodies, sheriff’s spokesman Steve Davis said.

“It appears to be a suicide mission,” Jefferson County Sheriff John Stone said.

When the two students began their attack just before lunch Tuesday, some students didn’t immediately realize what was happening.

“At first we thought it was just firecrackers,” one student told ABCNEWS. “Until we saw the black guns come out of the trench coats, and that’s when we knew it was real. And when we heard the bullets whiz by us. We knew that we better get out of here.”

Bullets ricocheted off lockers as students sprinted for the exits. Wade Frank, an 18-year-old senior, said he saw one of the killers shoot someone point-blank in the back with a 2-foot-long gun, possibly a sawed-off shotgun. “He was just casually walking,” Frank said. “He wasn’t in any hurry.”

At least 12 bombs were found throughout the school in the aftermath of the attack, some set up as booby traps, in the school and outside the building in knapsacks, Stone said. “It’s like walking through a minefield,” he said. “The bomb guys keep finding more and more of this stuff.”

“Some of these devices are on timing devices, some are incendiary devices and some are pipe bombs,” he told ABC’s Good Morning America. “Some are like hand grenades that have got shrapnel in them wrapped around butane containers.”

Explosives also were found in two cars in the school parking lot, with one bomb rigged to blow up a gas tank, Stone said. Also, a bomb was found in one of the gunmen’s homes.

Many parents had to wait anxiously for word about their children for hours after the shootings. They gathered at a nearby elementary school and answered questions from investigators, who were trying to identify the victims based on what they were wearing.

Although authorities told parents to go home and come back this morning, some refused to leave.

In a national address Tuesday night, President Clinton asked Americans to “wake up” to school violence. He said a team of grief counselors has been mobilized and will head to Littleton, Colo.

“If it can happen here, then surely people will recognize that they have to be alive to the possibility that it can occur in any community in America and maybe that will help us to keep it from happening again,” he said.

The two gunmen apparently belonged to a clique of outcasts called the “Trench Coat Mafia.” Fellow students said they wore long black coats every day, boasted of owning guns and disliked blacks and Hispanics.

Davis said the motive for the shootings was unknown and school officials had had no reports of trouble from the suspects.

Sean Kelly, 16, said the group had a video production class and made a video about guns they had. He also said that several members recently bragged about getting new guns, and that he heard members making derogatory remarks about blacks and Hispanics.

“They’re really dark people,” said Wes Lammers, 17. “There were a lot of jokes that one day they might snap or something.” “They were laughing after they shot, ” said student Aaron Cohn, who said he saw one of the gunmen pull a sawed-off shotgun out from under his coat. “It was like they were having the time of their life.”

Cohn also said one of the two shooters looked under a desk in the library and said “peek-a-boo” and then fired. Anyone who cried was shot again, and one girl begged for her life, but a shot ended her pleas.

Four youths were taken in for questioning after the attack. One was led away from the school in handcuffs and three were stopped in a field near the school. Authorities said the four were friends of the gunmen.

For much of the day, the scene around the sprawling school in Littleton, Colo., was chaos. Hordes of students streamed from a number of entrances, their hands on their heads. Anguished parents made frantic searches for their children.

At one point, a bloodied young man dangled from a second-floor window, his right arm limp, and was helped down by two SWAT team members.