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German media said the explosion occurred near the Federal Office for Migration in Zirndorf, Bavaria, where the cases of newly arrived refugees are processed. According to media reports, a suitcase packed with highly flammable aerosol cannisters was detonated around 200 yards away from the building.

Armed officers were rushed to the scene and a police operation is ongoing, according to a police spokeswoman. Bomb squad experts have also been called in to examine the debris. She added that witnesses heard a loud bang and discovered a burning suitcase on a footpath near the immigration centre.

SKY NEWS It is believed that a suitcase was detonated near the immigration centre

SKY NEWS Armed officers have been deployed to the scene

German media reported that police carried out a raid just yards from the reception centre on Wednesday. Witnesses described how people fled the scene in panic as a huge bang ripped through the quiet neighbourhood. The BR24 news website also reported witnesses as saying several Arab-looking men ran away from the scene after the blast, but it is not clear whether they were involved or merely fleeing the explosion. The German interior ministry this afternoon described the explosion as "small" and said that nobody had been injured. Bavarian police tweeted that there had been a "detonation" but reassured people there was "no explosion, no injuries, no threat".

Terror Attacks 2016 Sun, July 31, 2016 2016 has been an unforgettable year so far, terror attacks have occurred in the hundreds, both reported and unreported. We take a look at the acts of terrorism so far in 2016 Play slideshow AFP/Getty Images 1 of 36 Cars burn at the scene, as 13 people were left dead and 55 injured

A police spokesman said that a man and a woman planted the suitcase that exploded, confirming that nobody was hurt in the explosion. The man was described as around 30 years old, with shaved black hair and being of "a Mediterranean appearance". The woman was said to be about 25 years old, very slim, and wearing her black hair in a bun. Yesterday Bavaria state premier Horst Seehofer warned that "Islamist terror" had arrived in German following a spate of high profile attacks over the last week. There is no indication as yet that today's events are linked to terrorism.

SKY NEWS Germany is on high alert following a string of attacks

EXPRESS Zirndorf is in the southern German state of Bavaria

Bavaria, in southern Germany, has been the entry route for more than a million migrants and refugees who have flooded into the country over the last 18 months. Many have been settled in small towns across the region, with most being housed in reception centres at first before being found more permanent accommodation. Germany has been on edge following a spate of terror attacks over the last week, including an axe attack on a train and a suicide bombing at a music festival. A doctor died after being shot in a Berlin hospital yesterday in what marked the fifth horror attack to rock the counrty in just over a week.

Twitter An explosion has rocked an immigration office in Germany