I am using estab to get a regressions summary table as latex table.

Here is my code.

Code:
#delimit ;
esttab ols s1 s2 s3 using "table/t3.tex",
    replace b(4) se(4) star(* 0.10 ** 0.05 *** 0.01) nonum nonotes nogaps
    stat (N tempandsquared precipitation cityFE yearmonthFE r2,
    label("Observations""Temp and Sq.""Precipitation""City FE""Month-Year FE""R$^2$") fmt(0 4))
    mgroups("OLS" "2SLS (Mortality(log))", pattern(1 1 0 0) prefix(\multicolumn{@span}{c}{) suffix(}) span erepeat(\cmidrule(lr){@span}))  
    mtitles("(1)" "(2)" "(3)""(4)")
    label keep(pm10_10)
    substitute(\_ _);
#delimit cr
With these code, output is as below. Array



I want to make the header as the picture below.
What should I do? Array