Police are not saying whether they suspect deliberate
poisoning, but a provincial government official quoted by the China
Daily newspaper said the poison could have been put in the food on
purpose.
The restaurant's owner has been detained by police,
and the premises closed.
Initial reports in the state-controlled media said 41
people had died, including schoolchildren, but other estimates had the
figure of more than 100.
The BBC's Damian Grammaticas in Beijing says that
since then reports appear to have been censored, with references to the
number of casualties removed.
Questioning
The deaths in Tangshan began on Saturday morning,
when hundreds of people collapsed after eating breakfast in a fast-food
restaurant.
Investigators have sealed off an alley near the
restaurant, where its food was cooked at a stall.
Victims had eaten breakfast snacks such as dough
sticks and rice balls from the tiny fast-food outlet, a branch of the
Heshengyuan Soy Milk chain on Tangshan's main street.
Witnesses described how people began spitting blood
and then collapsed after taking just a few mouthfuls of the snacks.
Peng Yongqing, who owns a store next to the outlet,
said he saw one elderly man collapse after eating breakfast from the
outlet.
"It happened right there in front of my store," he
told Reuters news agency.
"One minute he was sitting there eating and the next
he stood up and keeled over. We all thought he was choking, we had no
idea what was wrong."
Mr Peng said the man had died on the way to hospital.
Many of the victims were boarding school students at
the Zuochang Middle School, which bought breakfast from the shop each
day.
Migrant construction workers were also among those
affected.
Sensitive time
Correspondents say mass poisonings are not uncommon
in China, and although most are due to negligence, some have been
deliberate.
In August 2001, 120 people fell ill in a restaurant
in Ningxiang, Hunan Province, after being poisoned by the owners of a
noodle factory.
And there have been several cases of poisoning in
schools in recent years.
Most recently, also in Hunan, 92 primary
schoolchildren were stricken by poison in their lunch.
