Several people in Humberside reported the prank on Thursday, in which an unknown offender rang different phone numbers pretending to be a police officer.
A statement released by Humberside Police on Saturday said that receivers of the hoax call reported being told that a relative had been killed in a fatal collision.
Detective Inspector Andy Robinson, from the force, said: “I would like to reassure people that we are treating these as hoax calls and take matters of this nature extremely seriously.
“As police officers, we would never contact a member of the public by telephone to inform them of such a tragic and distressing incident."
He added that anybody who receives a call from someone claiming to be a police officer should ask which force they are calling from, then call 101 from a different number if possible.
Anybody who receives a similar call or who has information which can help the investigation is asked to contact the force on 101 quoting log 588 of Thursday, May 6.
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