As the sun began to set on the golden spires and gilded finials of Bangkok’s Grand Palace, the gates waited to open for the return of a princess.

Since December 2022, Princess Bajrakitiyabha had been in hospital, having collapsed while out training her dogs. After nearly four years in a coma, the princess died earlier this week.

On Saturday afternoon, her body finally left the hospital in a royal funeral procession of flashing motorcycles and cars travelling through the city centre’s empty streets, which were closed to traffic but lined for kilometres by citizens dressed in black and officials in white suits with black armbands.

They had been waiting for hours for the princess’s arrival in a silver van, with her father, the king, in a cream-coloured car behind her. The officials present saluted, while the crowd – remaining seated on the sidewalk – silently bowed their heads towards their hands. Many were in tears.

From morning, mourners had gathered on the edges of the streets with umbrellas and fans to cope with the hot and humid conditions in the heart of the city.

Wanida Lainun, wearing a brooch with the princess’s image, told the Guardian her aunt was part of Princess Bajrakitiyabha’s project to help underprivileged people in Chiang Mai in the country’s north.

The princess, known affectionately in Thailand as Princess Bha, trained as a lawyer, and served the country in several official roles including as an ambassador to Austria and in the royal security command.

But it was the care she took for the ordinary citizens of Thailand, including campaigning for the rights of female prisoners, that those gathered on Saturday remembered.

“The work she’s done in Thailand has touched my heart,” said Anchalee, who asked that her last name not be used, and cited her project to help people during natural disasters. “Herself and her team go there right away to help them.”

After devastating floods hit Bangkok in 1995, Bajrakitiyabha and her mother personally cooked meals, packed medicine and waded into cut-off areas to deliver aid directly to the stranded, according to local media.

In October that year she founded the Friends in Need (of ‘Pa’) project, under the Thai Red Cross Society, that installed weather stations in high-risk areas to act as early-warning systems. The foundation helped people evacuate before disaster struck, provided frontline services and helped people affected by the floods out of poverty.

She was 47 years old when she died on Thursday evening. Anchalee, being the same age, said she had always felt close to the princess, whom she met as a college student. “She wouldn’t remember me, but I will always remember her,” she said.

Anchalee, who had been waiting on the streets for the procession since 10am, said she was shocked when the princess first fell ill. “We all hoped she could get better from the coma. We waited for years and we all prayed for her to get better.”

She had already waited hours in line earlier in the morning to participate in the funeral bathing ceremony at the Grand Palace that the king had invited the country to attend – a Buddhist ritual of pouring holy water into a ceremonial bowl placed before a portrait of the princess.

“We pray for the princess to go to a beautiful place in heaven,” Anchalee said.

The prime minister, Anutin Charnvirakul, led members of the Thai cabinet in performing the bathing rite, wearing the white suits that officials, including members of cabinet, civil servants and military officers, wear during royal funeral processions.

The government has yet to announce details of the funeral, but it has instructed officials to wear black and that flags be flown at half-mast for 15 days.

Towards the end of the day, government workers handed out free meals to the many mourners who remained outside the palace waiting to see the king leave.