A vehicle carrying Chinese nationals was hit by a suicide bomb in Pakistan's Balochistan province, Reuters reported, citing a government official.
"Two children have been killed and three injured in the attack," Liaquat Shahwani, a spokesman for the Balochistan government, said.
According to a police statement, the blast took place at the East Bay Road about 19:00 local time.
No group has claimed responsibility for the attack.
China has been involved in the development of the Gwadar port on the Arabian Sea as part of the China-Pakistan Economic Corridor, which is one of the parts of China's Belt and Road infrastructure project.