Four men broke into an elderly couple's home in Setagaya Ward, Tokyo, early Tuesday, killed the husband and made off with money and jewels, police said.

The intruders tied up Toshiyuki Ueno, 65, who owned a machinery plant in Saitama Prefecture, and his wife, Kiyomi, 64, before fleeing with the money, police quoted her as saying.

Ueno died shortly afterward. Police speculated that he suffocated because his nose and mouth had been covered.

The intrusion took place at around 4:55 a.m. One of the robbers stormed into the couple's bedroom just as the wife woke up to go to the bathroom, and demanded money.

While the first intruder took the money and jewels from the wife, the three others fought with Ueno when he resisted. Ueno was later found collapsed on his bed.

The wife managed to untie herself and call a security company about 45 minutes after the intruders escaped, police said, adding that she told them the intruders apparently fled with a wallet containing about 500,000 yen and jewels.

She was also quoted as saying that the four spoke broken Japanese, and that one was about 170 cm tall, wore a jumper and hid his face with a mask.

The intruders are believed to have entered the house by smashing a back door window.

According to police, the home was burglarized in November and about 15,000 yen was stolen. Ueno was away on a business trip to China at the time.

The home is located in a residential area about 300 meters northwest of Higashi-Kitazawa Station on the Odakyu Electric Railway line.