They were sent to Mohammad Yasin, Rushanara Ali, Rupa Huq, and Afzal Khan.
Muslims members of the British parliament have been sent a series of suspicious packages over the past 24 hours, prompting a response by police.
Officers were called to the parliamentary estate on Monday and again on Tuesday. Two people were hospitalised as a precaution before the items were deemed not to be hazardous.
Parliament has received four such packages over the past 24 hours, police told Business Insider. Three of the MPs in question have said the packages came with aggressive letters attacking their religion.
Mohammad Yasin received a package on Monday, his office confirmed to Business Insider. Rushanara Ali, and Rupa Huq have both tweeted to say they received similar packages. Afzal Khan also received a package but did not open it, his office told BI in a statement.
The packages sent to Yasin, Ali, and Huq contained letters advertising "Punish A Muslim Day," which listed Islamophobic actions and the number of points given for performing them, The Guardian reported.
The letter was also sent to households nationwide, said Tell MAMA, a charity that investigates anti-Muslim acts in the UK.
Huq told the BBC the package sent to her on Monday contained a "low-level noxious substance and an offensive letter."
A police spokeswoman told Business Insider in a statement on Tuesday morning:
"Police were called at 09:49 hours on Tuesday, 13 March to reports of a suspicious package at Norman Shaw Buildings, Victoria Embankment, Westminster.
"Specialist officers are on scene and the package is being assessed.
"The London Ambulance Service are on scene. No reported injuries."
A Parliament spokesman told BI that police were investigating potential links between the packages.
Two unidentified people were taken to hospital as a precaution following Monday's suspicious package report. One of them was a male member of Huq's staff, Huq confirmed.