NAIROBI, Kenya — Many people were feared trapped as a tall building collapsed Friday in Kenya’s capital, leaving a huge mound of concrete and more than a dozen floors stacked like pancakes, with little space between them.

The building was under construction when it collapsed at about 1 p.m. along a busy commercial street in Nairobi’s Eastleigh area, which is often crowded with thousands of traders and residents.

Nairobi police chief Issa Mohamud said the building had more than 10 upper floors under construction. Rescue operations were complicated, with police firing tear gas at people who had begun looting neighboring shops, as officers sought to clear the area and provide access to emergency response teams.

The Kenya Red Cross said its teams were on their way and urged people at the site to give responders space to work safely.

There was little in the way of heavy equipment immediately available. Hours later, a group of rescuers in hard hats were using poles stripped from trees to poke at the huge pile of rubble.

One excavator arrived on site and started moving the concrete bound with steel away so that the rescuers might reach the ground-level and basement floors that were said to have been rented out as shops while construction continued on the upper floors.

Residents said some of their loved ones who were trapped had made phone calls calling for help immediately after the collapse, but that their phones later became unreachable.

Building collapses are a recurring problem in Nairobi. County officials responsible for issuing building permits have been accused of failing to conduct adequate inspections to ensure developers comply with safety guidelines and construction standards.