He said the attackers were about to take Li away before passers-by came, and then they left the scene.
Lu said he phoned the police more than once before they came to check the scene, eight hours after the incident was reported.
"We called them three times and explained why we need them to come to the site because we were worried about the evidence. The marks on the road and around the vehicles are very slight. The weather in winter is quite wet and it could wipe everything off," he said.
He said Li could have been kidnapped, and the police should take it more seriously.
"The communication got broken somewhere. Every time we called the police, I need to tell the story again and again. They should get the information easily from the system," Lu said.
"I think the action is quite slow, because this is a very serious, criminal case. It should be one of the highest priorities of them."
A police spokesperson said they are investigating what happened.
- RNZ