London firefighters combed through a burned-out public housing tower Thursday in a grim search for missing people as police and the prime minister launched investigations into the deadly inferno, with pressure building on officials to explain the disaster and assure that similar buildings around the country are safe.

At least 17 people were killed as flames raced through the 24-story Grenfell Tower early Wednesday, trapping people inside their apartments. Many people remained unaccounted for Thursday, and officials weren't sure exactly how many were missing. But they expected the death toll to rise significantly.

London Police said an investigation had been launched to determine whether the blaze involved any crimes and Prime Minister Theresa May announced a public inquiry, a type of probe that's used to investigate issues of major public concern. In addition, London Mayor Sadiq Khan called for an interim report on the fire to be published this summer.

"People deserve answers. The inquiry will give them that," said May, the Conservative leader who set aside her efforts to form a new government Thursday to visit the scene of the blaze.

An angry crowd confronted Khan as he visited the high-rise.

"How many children died? What are you going to do about it?" asked 7-year-old Kai Ramos. As the boy pressed, the Labour politician pledged to get answers.

The tower is in the North Kensington neighborhood, a working-class, multi-ethnic area next to some of the richest neighborhoods in Britain. Some observers asked whether hazards in the Grenfell complex, which had 120 apartments that housed as many as 600 people, were ignored because its residents are mainly poor.

A tenant group had complained for years about the risk of a fire in the building, owned by the local government in the borough of Kensington and Chelsea.

Fire safety engineers were stunned at how rapidly the fire spread, engulfing the building in less than an hour in the middle of the night and preventing firefighters from reaching many people inside. Some jumped to their deaths rather than face the flames, and witnesses reported seeing small children thrown from the tower by their families in a desperate bid to survive.

Firefighters trying to race into the building were protected from the falling debris by police officers who placed riot shields over their heads.

Queen Elizabeth II praised the firefighters' bravery, and their commissioner noted the trauma they had seen. 

One officer was in tears after seeing someone plunge out a window, Fire Commissioner Dany Cotton told Sky News.

"We like to think of ourselves as 'roughty, toughty' and heroes - they are heroes - but they have feelings. People were absolutely devastated by yesterday's events," Cotton said.

Some parts of the tower were unsafe for firefighters to enter Thursday, so the fire department worked with structural engineers to shore it up so crews could conduct thorough searches for victims, Cotton said. Specially trained dogs were being brought in to aid the search. Police were unsure whether they would even be able to identify everyone.

In addition to those killed, ambulance crews took 74 people to hospitals after the fire. Thirty were still hospitalized on Thursday, with 15 in critical condition.

One of the first victims was identified - Mohammed Alhaj Ali, a 23-year-old Syrian refugee studying in London and hoping to return to help his war-torn country.

Fears grew for others, such as Bassem Choukeir, his wife Nadia, her mother Sariyya and the couple's three daughters Mirna, Fatmeh and Zaynab. They lived on the 22nd floor, and the Lebanese Embassy has listed them as missing.

Families were also concerned about two young Italian architects who were missing. Gloria Trevisan and Marco Gottardi, both 27, lived on the 23rd floor.

"The flames are in the living room. There are flames around us," Trevisan told her mother in a farewell phone call thanking her for all she had done, family lawyer Maria Cristina Sandrin said. Gottardi told his father in separate calls that suffocating smoke in the stairs kept them inside their apartment and awaiting rescue.

Authorities have refused to speculate on what could have started the blaze. But the focus has turned to renovations completed last year that added decorative touches to the building.

The project included installing insulated exterior cladding, double-glazed windows and a communal heating system.

"Some very hard questions have to be asked, and some very hard questions must be answered" about the cladding, building regulations, fire protections and more, Labour Party leader Jeremy Corbyn said.

"Every single person that lives in a high rise apartment today is going to be thinking, 'How safe am I?'"

Britain's government has ordered checks at towers going through similar renovations, and some London neighborhood authorities said Thursday they'd do extra fire-safety assessments at public housing high-rises.

More than 1 million pounds ($1.27 million) has been raised to help victims of the fire. 

Volunteers and charities worked through the night to find shelter, food and clothes for people who had lost everything.

By Thursday, community centers had been so overwhelmed by food and clothing donations that they started turning away new donations.

St. Clement's Notting Dale, a church near the tower, was turned into an informal center for people searching for missing friends and family.

Signs bearing a missing persons' hotline number were tied to a fence. By the church's front door, residents taped signs looking for information about Khadija Saye, last seen on the 20th floor, and Mariem Elggwahry, last seen on the 19th floor at 2:30 a.m. Wednesday.

At Latymer Community Church a few blocks away, messages of hope and condolences were written on a board in English, Arabic and Spanish.

"Praying for auntie," one message read.

AP