SAMUT SAKHON, Thailand (AP) — Thousands of people lined up for coronavirus tests in a province near Bangkok on Sunday, as Thai authorities scrambled to contain an outbreak of the virus that has infected nearly 700 people.

Triple lines of mainly migrant workers stretched for around 100 meters in one location alone, at Mahachai in Samut Sakhon province, as health officials in mobile units methodically took nasal swabs. There were three locations in total in the area.

Nearby, razor wire and police guards blocked access to the Klang Koong, or Central Shrimp, seafood market — one of Thailand's largest — and its associated housing, the epicenter of the new cluster.

Thailand’s Disease Control Department said Sunday that they found 141 more cases linked to the market outbreak. On Saturday, the department reported 548 cases, Thailand's biggest daily spike, sending shockwaves through a country that has seen only a small number of infections over the past several months due to strict border and quarantine controls.

The new outbreak has been traced to a 67-year-old shrimp vendor at the seafood market.

Health officials say most of those who have been infected are migrant workers from Myanmar. The workers live close to the market in crowded accommodations, raising fears that the virus could spread exponentially.

Samut Sakhon is 34 kilometers (21 miles) southwest of Bangkok, the capital.

Samut Sakhon's governor has imposed a night curfew and other travel restrictions until Jan. 3. Many public places in the province, including shopping malls, schools, cinemas, spas and sports stadiums, have been ordered closed.

At the Mahachai seafood market, there was a listless atmosphere as idle workers sat around, unable to leave the area. Food supplies were brought to the entrance but had to be offloaded. Masked residents of the housing around the market piled provisions onto trolleys and took them away.

For some, the concern was economic.

“I am worried because I can’t do anything at all and my employees can’t go out either, so we can’t do anything. The loss is huge,” said one seafood merchant, 55-year-old Thanawan Watchanapraphan.

Wanida Imphanchai, another merchant, paced near the market's blocked entrance, telling the police on duty that she had a negative coronavirus test just days ago and should be allowed to leave. She showed them the document on her phone, but they politely declined her request.

“How can I live like this? The virus comes but I can’t see it. If something happens to me, it will be messy,” Wanida said before walking away.

With fewer than 5,000 cases and 60 deaths, Thailand has been able to largely control the virus. Prior to the current outbreak, there had been very few cases of local transmission in recent months, as life returned largely back to normal.