ATHENS- After 12 envelopes with an unknown power were sent to Greek college campuses the day before, another six were discovered on Jan. 11, authorities said, this time to universities in Ioannina, Rethymno, Patra, Corinth and Lamia received similar envelopes, as well as the private Mediterranean College in Thessaloniki.

None were opened and the fire department sent sent to collect them, said Kathimerini, with no idea yet who has sent the spate of suspicious envelopes or why although it comes on the heels of recent bombings outside the SKAI TV station and an Athens church with worries growing over more terrorist activities.

The initial dozen envelopes were sent to campuses were in Athens, the islands of Crete, Lesvos, Cephalonia and Corfu, the northwestern town of Arta, Sparta in the Peloponnese and the central city of Volos.

According to the results of a state lab examination, the powder was made of “irritants used in the production and improvement of adhesives and printing ink,” the paper said, without any indication of the level of toxicity or danger.

The Civil Protection Agency also warned post offices and universities against opening any package deemed suspicious.

All the letters were reportedly sent from Kerala in southern India and were labeled with the words “Islamic content” written in English and each, all of them yellow, was said to have had a seal and four Indian stamps.

The investigation was initially undertaken by the police’s anti-terror department, while the envelopes were handled by an expert team of the fire department which deals with chemical and biological threats.

More than a dozen people – university and postal staff – received medical attention as a precaution but none, reportedly, suffered any health problems, the paper and media reports had said initially.

None of the people examined — four postal workers and five university staff members — displayed any symptoms typically caused by harmful chemicals.

Paramedics prepare to enter a college after employees received a suspicious envelope, in the northern port city of Thessaloniki, Greece, Friday, Jan. 11, 2019. (AP Photo/Giannis Papanikos)