Septi and Jamaliah Rangkuti with their daughter Raudhatul Jannah and sons Jumadi and Arif Pratama. Photograph: AFP/Getty Images

An Indonesian couple who were reunited with their daughter 10 years after a tsunami snatched her from their arms now claim to have found their son, who was also swept away in the disaster.

Jamaliah and Septi Rangkuti had an emotional reunion with the teenager they believe is their son on Monday, bringing their whole family together for the first time in 10 years.

Arif Pratama Rangkuti was carried off with his younger sister when a tsunami hit Indonesia's westernmost Aceh province in 2004, killing more than 170,000 people there and tens of thousands in other countries.

Arif's sister, Raudhatul Jannah, was reunited with the parents in June after a relative spotted a girl in an Aceh village who bore a striking resemblance.

On Tuesday the couple said their son, now 17, had also been returned, thanks to media coverage of the reunion with their daughter. "It's true, he's our son. We're now preparing to take him home," Septi Rangkuti said.

His wife wept as she clutched the teenager, who seemed shy and overwhelmed. "I prayed every night, because inside I believed that my child was still alive," she said. "My husband has always been restless at home because of this. He would say that our son is still alive."

The family were reunited at the home of a couple who found the boy asleep one night outside the internet cafe they run in Payakumbuh, in West Sumatra province. The teenager has been homeless for years, sleeping in outdoor markets and abandoned shops.

Lana Bestari and Windu Fajri let the boy sleep at their cafe for several months, giving him food and clothes on his regular visits. Bestari got in touch with the Rangkutis after she saw a photograph of Arif as a child on television. "I was shocked – there was a photo of a boy I recognised very well. I recorded his image on my smartphone," she said.

The boy had told her only that he had come from Medan, in North Sumatra province. If he is indeed the couple's son, it is unclear how he made the journey there from Aceh.

After seeing the news, Bestari and her husband searched for the boy, whom they had named Ucok. The teenager spoke to the Rangkutis on the phone, and the couple and their youngest son and relocated daughter immediately travelled to meet him.

The couple believe the children were rescued together by fishermen who took them to the Banyak islands off the coast of Aceh. The girl was taken in by a family in Aceh, who renamed her Wenni. A fisherman wanted to adopt both of them, but ended up taking just the girl as he did not think his family could provide for two more children.

Sources: theguardian