Armed officers will be used in the derby day policing operation in Sheffield today.
They will be among 500 officers on duty in Sheffield today to try to keep fans safe before, during and after the game at Bramall Lane.
Sheffield United host Sheffield Wednesday in the second Steel City fixture of the season tonight, with the game due to kick off at 7.45pm.
Sheffield's District Commander, Chief Superintendent Shaun Morley, who is overseeing the policing operation, said: "Sheffield is buzzing today as it prepares for this latest derby and it promises to be an exciting game for everyone.
"We know that you’ll all be looking forward to enjoying the football with your friends and family tonight and if you are venturing into town to watch the match at either Bramall Lane or at a licensed premise, you can expect to see a heightened police presence.
"This will include both armed and unarmed officers. This isn’t in response to a particular threat so please don’t be alarmed. All of our officers are here this evening to keep you safe, to engage with the public and to prevent any crime or disorder.
"We have been working with both clubs and a range of partner agencies to ensure that this evening’s game is enjoyable and safe for everyone. Please enjoy yourselves tonight, stay safe and look after one another."
Turnstiles are expected to open at Bramall Lane at 6.30pm.
Fans have been warned to expect extra searches and heightened security.