The health commission of Heilongjiang province reported 33 new imported confirmed cases presenting symptoms of COVID-19 on Saturday and Sunday.
All the cases, including four patients in serious condition, were Chinese citizens returning from Russia.
After flying from Moscow to Vladivostok in Russia's Far East, they traveled 190 kilometers by car and entered China in Suifenhe.
All the infected people have been sent to a hospital.
Medical teams drawing on about 120 professionals from nearby regions arrived in the city soon thereafter, according to Suifenhe Daily.
A team of 34 medical workers from Mudanjang Hongqi Hospital arrived on Sunday evening with medical supplies, including protective suits, N95 masks and sterilizing equipment.
The highway port in Suifenhe will be closed on Monday, according to a statement on the city government's website on Friday.
The province also reported 40 new imported asymptomatic cases over the weekend.
As of Sunday, Heilongjiang had 42 imported confirmed cases and 60 imported asymptomatic cases. No local transmission was reported.