By Bernie Woodall and Zachary Fagenson

PARKLAND, Fla. (Reuters) – As families prepared on Friday to bury victims of another U.S. mass shooting, grief mixed with anger amid signs of possible lapses in school security and indications that law enforcement may have missed clues about the suspected gunman’s plans.

One distraught mother who said she had just spent two hours making funeral preparations for her 14-year-old child expressed disbelief that a gunman could just stroll into school and open fire, and she appealed to President Donald Trump to take action.

Bob Ossler, chaplain with the Cape Coral volunteer fire department, places seventeen crosses for the victims of yesterday’s shooting at Marjory Stoneman Douglas High School on a fence a short distance from the school in Parkland, Florida, February 15, 2018. REUTERS/Jonathan Drake

Nikolas Cruz, 19, identified as a former student at Marjory Stoneman Douglas High School in Parkland, Florida, who had been expelled for disciplinary problems, walked into the school on Wednesday and opened fire with an assault rifle, killing 17 students and facility members and injuring 15 others, police said.

The shooting has raised questions among anguished parents about the adequacy of school security measures and renewed a national debate on Capitol Hill and elsewhere about the epidemic of gun violence in American schools.

“How do we allow a gunman to come into our children’s school? How did they get through security? What security is there?” Lori Alhadeff shouted into the camera in an emotionally raw appearance on CNN.

“The gunman, the crazy person, just walks right into the school, knocks down the window to my child’s door and starts shooting, shooting her …,” cried Alhadeff, whose daughter Alyssa was among the dead.

Cruz, charged with 17 counts of premeditated murder, made a brief initial court appearance on Thursday, in which he was ordered held without bond.

“He’s a broken human being,” his lawyer, public defender Melissa McNeill, told reporters. “He’s sad, he’s mournful, he’s remorseful.”

Daniel Journey (C), an 18-year-old senior at Marjory Stoneman Douglas High School in Parkland, attends a community prayer vigil for victims of yesterday’s shooting at his school, at Parkridge Church in Pompano Beach, Florida, February 15, 2018. Journey said he lost two friends he had known and grown up with since they were seven years old in the shooting. REUTERS/Jonathan Drake

“PROFESSIONAL SCHOOL SHOOTER”

Cruz may have foreshadowed the attack in a comment on YouTube, investigated by the FBI. The Federal Bureau of Investigation disclosed it received a tip in September about the message that read: “I’m going to be a professional school shooter,” by a user named Nikolas Cruz.

However, FBI agents had no information pointing to the “time, location or true identity” of the person behind the message, Robert Lasky, special agent in charge of the FBI’s Jacksonville office, told reporters.

YouTube ultimately removed the material in question, and the FBI’s inquiry was dropped until the name Nikolas Cruz surfaced again in connection with Wednesday’s massacre.

Authorities say Cruz, identified as a former student at Stoneman Douglas High who had been expelled for disciplinary problems, walked into the school shortly before dismissal time, pulled a fire alarm and opened fire as students and teachers streamed out of classrooms into the halls.

The sheriff said Cruz arrived at the school by way of the Uber ride-sharing service and left the scene on foot, mixing in “with a group that were running away, fearing for their lives.”

He walked into a Walmart, bought a beverage at a Subway outlet inside the store, then visited a McDonald’s before he was spotted and detained by a police officer in the adjacent town of Coconut Creek, Israel said.

Former classmates have described Cruz as a social outcast with a reputation as a trouble-maker, as well as someone who was “crazy about guns.” The sheriff has said some of the online and social media activity Cruz engaged in was “very, very disturbing.”

Wednesday’s shooting ranks as the greatest loss of life from school gun violence after the 2012 shooting rampage at Sandy Hook Elementary School in Newtown, Connecticut, that left 20 first-graders and six adult educators dead.

People attend a candlelight vigil for victims of the shooting at nearby Marjory Stoneman Douglas High School, in Parkland, Florida, February 15, 2018. REUTERS/Carlos Garcia Rawlins

“It is not enough to simply take actions that make us feel like we are making a difference,” Trump said at the White House in a speech that emphasized school safety and mental health while avoiding any mention of gun policy. “We must actually make that difference.”

Democrats in the U.S. House of Representatives criticized the Republican leadership on Wednesday for refusing to take up legislation on tightening background checks for prospective gun buyers.

Some gun control proponents and legal experts said Wednesday’s shooting might have been averted if Florida were among the handful of U.S. states with laws allowing police and family members to obtain restraining orders barring people suspected of being a threat from possessing guns.

Cruz had recently moved in with another family after his mother’s November death, said Jim Lewis, a lawyer representing the family, bringing his AR-15 along with other belongings.

The family believed Cruz was depressed, but attributed that to his mother’s death, not mental illness, Lewis said.

For graphic on Florida school shooting, click: http://fingfx.thomsonreuters.com/gfx/rngs/FLORIDA-SHOOTING/010060XH1SW/shooting.jpg

(Additional reporting by Brendan O’Brien in Milwaukee)