Authorities in Nairobi learned just before dawn last Thursday that gunmen had attacked a college in northeast Kenya. Seven hours elapsed before police commandoes trained to deal with such a situation flew to the scene, a delay which may have contributed to the high death toll of 148 and which points to deeper problems as Kenya confronts a growing threat from Islamic extremists.

Public anger about the delayed response was apparent Tuesday as about 250 students demonstrated in Nairobi, the capital. At one point they passed a truck carrying security forces with red berets and rifles.

"Where were you?" the students shouted angrily. The troops did not respond. They also banged on the sides of a police vehicle and converged briefly outside Kenyan police headquarters, again demanding: "Where were you?"

The Kenyan military, which has a barracks in the town of Garissa where the attack by the Islamic extremist group Al-Shabaab occurred, was the first to respond with some help from local police officers, the government has said. The police department's paramilitary Recce tactical unit, which is trained in close-quarters combat and hostage rescues and is based in Nairobi, was briefed about the attack but was put on standby because the military said it could handle the attackers, said a senior police officer who was involved in Thursday's actions.

It was only after hours had gone by and the military had suffered some casualties that a decision was made to send in the Recce unit, he said. The official spoke only on condition of anonymity because he is not authorized to speak to the press. Military spokesman Col. David Obonyo did not immediately answer phone calls seeking comment.

With police helicopters not operational because of mechanical problems, the Recce Squad flew the 200 miles (325 kilometers) to Garissa aboard two small planes which could not fit the whole squad, forcing other members to travel by road. Once the tactical team went into Garissa University College at 5 p.m. -- almost 12 hours after the attack had started -- they killed the four gunmen and secured the campus within a half hour. By then, almost 150 students and others were dead.

Kenya has vowed severe retaliation against Al-Shabaab and its military on Monday announced air strikes against Al-Shabaab camps in Somalia.

The problem of a lack of a coordinated response to an extremist attack also plagued Kenya's security forces after Al-Shabaab attacked Nairobi's Westgate Mall in September 2013, killing 67 people. The army stormed the mall without coordinating with the Recce unit whose members had already infiltrated the mall and were closing in on the attackers, leading to a friendly fire incident that killed one Recce officer and forced the elite police team to withdraw.

"We have refused to learn from the Westgate attack. What was the Kenyan army doing for seven hours before the Recce team came in? Were they just hanging about? We saw KDF (Kenya Defense Force or the Kenyan army) camping outside of the university as the killing went on inside," said Patrick Gathara, a commentator and award-winning political cartoonist.

Inter-service rivalries may also be playing a role in coordinating responses to extremist attacks and security officials also complain of under-funding and corruption. For example, a government commission looked into the procurement of the grounded police helicopters, suspected fraud and recommended an audit of their purchase.

"The systemic corruption that afflicts all our institutions infects our security services too. This continues to be the deadweight our efforts against terrorism have to carry," said Kenyan corruption expert John Githongo, currently a visiting scholar at Stanford University's Haas Center for Democracy, Development and the Rule of Law.

A number of Kenyan universities have increased security following the Garissa attack, hiring more guards and urging students to be vigilant. But some students are fuming over what they allege is a government failure to act on intelligence and prevent violence by Al-Shabaab, the Somali-based extremist group that has vowed more attacks in Kenya as reprisal for Kenya having sent troops into Somalia.

"We are not safe," Kenyan students chanted on Tuesday.

Their slogan captured the unsettled mood in many Kenyan schools, and the country as a whole.

"We might be next," said Walter Mutai, a 22-year-old statistics student at Moi University. "These people, they can target anywhere."

"I feel vulnerable as a Kenyan citizen," said Ricky Thomas Nyakach, a 22-year-old student who plans to study law this year. Kenya, he said, is struggling with a "badly flawed security system" in which security forces have bad equipment as well as low morale because of inadequate salaries.

Wearing a suit and tie, Nyakach stood in a park before the rally and said student demands include "a total overhaul" of Kenya's security apparatus, the construction of a memorial in honor of those killed at the Garissa college and the payment of funeral expenses and about $22,000 in compensation for the families of the victims.

The protesters presented a petition to the office of President Uhuru Kenyatta and received an official signature of receipt, but some were skeptical about whether they could achieve meaningful change.

The demonstration was mournful at times. There were signs that read: "You remain in our hearts!" and "RIP comrades."

Students and other Kenyans gathered at dusk for a vigil honoring the victims, lighting candles, holding flowers, reading their names aloud and erecting a white wooden cross for each of those who were killed in Garissa.

On Tuesday, police presented in court five suspects, three of whom allegedly supplied guns to the four men who carried out the Garissa killings. The court granted police 30 more days to investigate the suspects before charging them in court. Police said they want more time to investigate a sixth suspect, a Tanzanian citizen who is being held in Garissa. The Interior ministry had said they had arrested the Tanzanian with grenades hiding in the ceiling, but the police charge sheet says he was arrested under a bed and was not a student at the university.