Emergency services rushed to the Dalkeith store shortly after 9pm on Friday following reports of “chemical incident”.
Three fire engines and a number of police cars were on the scene on the town’s Bonnyrigg Road.
Some customers took to social media to express their shock. Billy Sneddon wrote on Facebook: “Medical incident at Tesco Dalkeith, no one is allowed to leave the scene.”
Another user said: “Police everywhere and have stopped people from leaving the store and entering the car park, people being told to tell the police straight away if they feel unwell.”
A police spokesman said: “Police in Midlothian were in attendance in Bonnyrigg Road in Dalkeith following a possible hazardous material chemical incident at the Tesco store.
“Officers were called to support the Fire and Rescue Service with an evacuation process.
“Nobody has been injured.”
The Scottish Fire and Rescue service said: “The store was evacuated so that firefighters wearing breathing apparatus could conduct a full investigation but they found no hazardous substances.”
One female was checked over by medics at the scene but did not require further treatment.
Fire crews departed at 10:41pm.
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